[ci skip] Update upgrade guide from GitLab CE to GitLab EE for 8.15

Following the steps from https://gitlab.com/gitlab-org/release-tools/blob/master/doc/release-candidates.md#creating-rc1.

See merge request !959

Fix css lint

I merged [CE->EE](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/953) with [failing css lint](https://gitlab.com/gitlab-org/gitlab-ee/builds/7216539), this is a fix.
It was caused by https://gitlab.com/gitlab-org/gitlab-ee/commit/d6d22a5dbd2ee04b59b2a80b3b6228575c3ea3ec on CE side.

@iamphill Please take a look if fixes are OK. If no, please send a separate MR to fix it.

See merge request !956

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>

CE upstream

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)

	both modified:   .gitlab-ci.yml
	deleted by them: app/assets/stylesheets/pages/admin.scss
	both modified:   app/assets/stylesheets/pages/issuable.scss
	both modified:   app/controllers/projects/issues_controller.rb
	both modified:   app/helpers/projects_helper.rb
	both modified:   config/routes/group.rb
	both modified:   doc/api/merge_requests.md
	both modified:   lib/api/users.rb
	both modified:   spec/controllers/projects/issues_controller_spec.rb
	both modified:   spec/finders/merge_requests_finder_spec.rb
	both modified:   spec/services/projects/create_service_spec.rb
	both modified:   spec/services/system_note_service_spec.rb

CE commits: https://gitlab.com/gitlab-org/gitlab-ce/compare/14046b9c734e5e6506d63276f39f3f9d770c3699...50a784482e997cc039015e24b37d3f8a01a9cd3e

See merge request !953

EE-specific changes for gitlab-org/gitlab-ee#1137

## Summary

- gitlab-org/gitlab-ee#1137 is a `technical debt` issue to clean up the EE protected branch access levels (for users and groups) implementation.
- Some of this cleanup bleeds over to code shared by CE and EE. This portion is covered in this CE merge request: gitlab-org/gitlab-ce!7821

## References

- Closes #1137 

## Tasks

-  [#1137/!7821/!927] Follow-up from restricting pushes / merges by group
    - [x]  Implementation
        - [x]  Prefer `validates` with `:uniqueness` option!
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_16390918
        - [x]  Could this be moved into `ProtectedBranchAccess`?
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_16391013
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_16391018
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_16391023
        - [x]  Please name controller action specs after the method and action: `describe "GET project_groups"`
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_16391093
        - [x]  I think we need more extensive integration specs here
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_16391229
        - [x]  Does this need to be a proc?
            - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/645#note_17145530
    - [x]  Tests
        - [x]  CE Passing
        - [x]  EE Passing
    - [x]  Meta
        - [x]  CHANGELOG entry created
        - [x]  EE branch has no merge conflicts with EE `master`
        - [x]  CE branch has no merge conflicts with CE `master`
        - [x]  Squashed related commits together
    - [x]  Review
        - [x]  CE Endboss
        - [x]  EE Endboss
            - [x]  Break javascript, make sure integration specs catch the failure
    - [ ]  Merge
        - [x]  CE
        - [ ]  EE


See merge request !927

[ci skip]

[ci skip]

[ci skip]

[ci skip]

Remove wrong '.builds-feature' class from the MR settings fieldset

EE MR for gitlab-org/gitlab-ce!7930

See merge request !947

Fix milestone total weight is missing on the milestone page

Fixes #1340

See merge request !944

- Move `ProctedBranchAccessEe` to `EE::ProtectedBranchAccess`. This is a lot
  cleaner, and has a precedent (`EE::Group`).

- Include `EE::ProtectedBranchAccess` inside `ProtectedBranchAccess`, instead of
  including both in the model classes. `EE::ProtectedBranchAccess` depends on
  `ProtectedBranchAccess` - this is a good way to model that dependency.

- Remove author credit from CHANGELOG entry

Allow public access to some Tag API endpoints

Continuation of #4269.

See merge request !7896

Reenables /user API request to return private-token if user is admin and requested with sudo

## What does this MR do?

Reenables the API /users to return `private-token` when sudo is either a parameter or passed as a header and the user is admin.

## Screenshots (if relevant)

Without **sudo**:

![Screen_Shot_2016-11-21_at_11.44.49](/uploads/ebecf95dbadaf4a159b80c61c75771d9/Screen_Shot_2016-11-21_at_11.44.49.png)

With **sudo**:
![Screen_Shot_2016-11-21_at_11.45.52](/uploads/f25f9ddffcf2b921e9694e5a250191d3/Screen_Shot_2016-11-21_at_11.45.52.png)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #24537

See merge request !7615

Update outdated visible content spec descriptions

This fixes some spec descriptions that were not fixed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7947.

See merge request !7971

Fix Backup::Manager#remove_old

Closes #25399

See merge request !7972

Fix typos in API doc examples

## What does this MR do?

Fixes a typo in the API docs. The `curl` examples in [build_triggers.md](doc/api/build_triggers.md) and [build_variables.md](doc/api/build_variables.md) all have a typo in the auth header. They all say `PRIVATE_TOKEN` when it should be `PRIVATE-TOKEN`.

## What are the relevant issue numbers?
Fixes #24565

See merge request !7514

Run builds with runners with tags gitlab-org and 2gb

## What does this MR do?

Added `gitlab-org` and `2gb` tags for jobs in `.gitlab-ci.yml`. So builds will be picked up by `gitlab-shared-runners-manager-X.gitlab.com runners`

## Are there points in the code the reviewer needs to double check?

Only `.gitlab-ci.yml`

## Why was this MR needed?

https://gitlab.com/gitlab-com/infrastructure/issues/714

## Screenshots (if relevant)


## Does this MR meet the acceptance criteria?

- [ ] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

https://gitlab.com/gitlab-com/infrastructure/issues/714

See merge request !7757

Use the pagination helper in the API

EE port of gitlab-org/gitlab-ce!7920.

See merge request !942

Grapify the issues API

Related to #22928

See merge request !7968

Update GLU index for new report, broken links + typos

## What does this MR do?
Update text on GLU documentation for spelling and new State of DevOps book. 

/cc @axil

See merge request !7962

Bump Git version requirement to 2.8.4

Following gitlab-org/omnibus-gitlab!1108, the install doc and README should be updated too.

See merge request !7878

Update Redis Sentinel HA password examples

Fix Redis HA documentation to make sure `redis['master_password']` is used instead of the regular `redis['password']` to configure the `gitlab-rails` instance as the first will work in all scenarios. 

cc @jnijhof

See merge request !943

Bump gitlab-shell version to 4.0.3

See merge request !7953

Move admin hooks spinach to RSpec

https://gitlab.com/gitlab-org/gitlab-ce/issues/23036

See merge request !7942

Move admin logs spinach test to RSpec

https://gitlab.com/gitlab-org/gitlab-ce/issues/23036

See merge request !7945

Signed-off-by: Rémy Coutable <remy@rymai.me>

Add a link to the "Guidelines for implementing Enterprise Edition feature" page

See merge request !941

Signed-off-by: Rémy Coutable <remy@rymai.me>