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

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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

Use the pagination helper in the API

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

See merge request !942

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

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

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

See merge request !941

- Over `validates_uniqueness_of`

- EE-specific protected branch access level code lives in this new module, while
  CE or CE/EE code lives in the existing `ProtectedBranchAccess` module. This
  allows us to make changes without introducing conflicts.

- The access level model classes first include `ProtectedBranchAccess`, followed
  by `ProtectedBranchAccessEe`, which preserves the inheritance chain:

  {Push,Merge}AccessLevel > ProtectedBranchAccessEe > ProtectedBranchAccess

[EE] Update API spec files to describe the correct class

Port of gitlab-org/gitlab-ce!7718 to EE.

See merge request !940

Include note about using user_filter syntax with special chars

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/1201

See merge request !882

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

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

CE upstream merge

- [x] .gitlab-ci.yml
- [x] Gemfile.lock
- [x] app/assets/stylesheets/pages/issuable.scss
- [x] app/controllers/concerns/lfs_request.rb
- [x] app/controllers/projects/git_http_controller.rb
- [x] app/helpers/issuables_helper.rb
- [x] app/models/concerns/protected_branch_access.rb
- [x] app/models/protected_branch/merge_access_level.rb
- [x] app/models/protected_branch/push_access_level.rb
- [x] app/services/system_note_service.rb
- [x] app/views/shared/issuable/_filter.html.haml
- [x] app/views/shared/issuable/_form.html.haml
- [x] app/views/shared/issuable/form/_metadata.html.haml
- [x] db/schema.rb
- [x] doc/web_hooks/web_hooks.md
- [x]  features/steps/project/wiki.rb
- [x] lib/api/projects.rb
- [x] lib/gitlab/git_access.rb
- [x] spec/features/security/project/private_access_spec.rb
- [x] spec/features/security/project/public_access_spec.rb
- [x] spec/mailers/notify_spec.rb
- [x] spec/services/merge_requests/merge_service_spec.rb
- [x] spec/services/merge_requests/refresh_service_spec.rb
- [x] spec/services/projects/destroy_service_spec.rb

Merged changes https://gitlab.com/gitlab-org/gitlab-ce/compare/858602ea153056f6cbfeeb4114ea6e29aba03a7a...14046b9c734e5e6506d63276f39f3f9d770c3699

See merge request !937

Prevent remote mirrors from failing when project is in pending_delete

We noticed on GitLab.com that remote mirrors were not even running.
UpdateAllRemoteMirrorsWorker was failing on a project that was in
pending_delete, preventing any workers from running.

Closes gitlab-org/gitlab-ce#23650

See merge request !938

The models were incorrectly merged (this would have been avoided if !927
was merged in, but that MR is still review) leading to a few spec failures.

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We noticed on GitLab.com that remote mirrors were not even running.
UpdateAllRemoteMirrorsWorker was failing on a project that was in
pending_delete, preventing any workers from running.

Closes gitlab-org/gitlab-ce#23650

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

Restore changes for api spec files

Fix error in rspec Users

Delete extra space Repositories-spec

Speed up project snippet security request specs

Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/24899

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7779 and
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7813

EE sibling of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7890

See merge request !939

Save some queries on issuable dashboard.

EE version of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7760.

See merge request !935

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