CE upstream

Could you guys please resolve next conflicts (the conflicts just committed to the branch):

@dzaporozhets - `app/views/layouts/nav/_project_settings.html.haml`

@iamphill `app/views/projects/_builds_settings.html.haml` and `app/views/projects/edit.html.haml`

@annabeldunstone `app/views/projects/_home_panel.html.haml`

@jschatz1 - `app/views/shared/issuable/_form.html.haml`

- [x] `app/views/layouts/nav/_project_settings.html.haml`
- [x] `app/views/projects/_builds_settings.html.haml` 
- [x] `app/views/projects/edit.html.haml`
- [x] `app/views/projects/_home_panel.html.haml`
- [x] `app/views/shared/issuable/_form.html.haml`
- [x]  `app/views/layouts/nav/_project.html.haml`
- [x]	`app/views/projects/hooks/index.html.haml`

See merge request !425

These specs do not exist in CE and don't add anything useful themselves.
There's no application code that initializes a JiraIssue instance and it
currently behaves exactly the same as a regular ExternalIssue.

Fix nil user handling in UpdateMirrorService

Previously an exception was hit quite frequently:

```
NoMethodError: undefined method `can?' for nil:NilClass
  app/services/projects/update_mirror_service.rb:9:in `execute'
    unless current_user.can?(:push_code_to_protected_branches, project)
  lib/gitlab/metrics/instrumentation.rb:153:in `execute'
    retval   = super
  app/workers/repository_update_mirror_worker.rb:13:in `perform'
    result = Projects::UpdateMirrorService.new(@project, @current_user).execute
  lib/gitlab/sidekiq_middleware/memory_killer.rb:17:in `call'
    yield
  lib/gitlab/sidekiq_middleware/arguments_logger.rb:6:in `call'
    yield
...
(26 additional frame(s) were not displayed)
```

Closes #605

See merge request !434

Remote Mirrors should be disabled by default

REF: #548 

See merge request !428

Closes #605

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

[ci skip]

Reduce number of fog gem dependencies

Currently supported:

* AWS
* Azure
* OpenStack
* Google
* local storage

Closes #15352

See merge request !4396

Cache project build count. Closes #18032

See merge request !4377

Move feature specs for shortcuts to valid directory

This MR moves tests to valid directory that matches our namespace we use in code.

See merge request !4433

Cache assigned issue and merge request count. Closes #18036 and #18035

See merge request !4378

Clicking search pill focuses field

When clicking the pill in the search field, it now focus the field. Previously you would have to make sure you click in the field.

Fixed an issue where clicking out of the field wouldn't remove the focus
outline

Also reduced some of the HTML to remove what isn't needed

See merge request !4279

Fix serious performance bug with rendering Markdown with InlineDiffFilter

Nokogiri's `node.replace` was being unnecessarily called for every text node in
the document due to a comparison bug. The code previously was comparing the
HTML representation of the full document against the text node, which would
always fail. Fix the comparison to just compare the modified text.

Closes #18011 


See merge request !4392