Sync 8-8-stable-ee to master

I solved some merge conflicts that arose when merging CE 8-8-stable (which contains the latest master branch) into 8-8-stable-ee.

See merge request !398

Tag API calls to /internal/authorized_keys

See merge request !396

CE upstream

See merge request !389

Fix minor typos in admin health check page

Fix minor typos from gitlab-org/gitlab-ce!3888

cc/ @DouweM @twk3 

See merge request !4134

Clean up EventsHelper spec

Extracted from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4090

See merge request !4133

Enable the Rubocop DeprecatedClassMethods cop

This reports uses of `File.exists?` and `Dir.exists?`, which were both
deprecated in Ruby and will eventually be removed in favor of `.exist?`.
Also fixes all existing uses of the deprecated methods.

See merge request !4087

Codestyle changes to make sure we have space around operators (EE)

This will introduce fixes for gitlab-org/gitlab-ce#17398 so after
gitlab-org/gitlab-ce!4112 gets merged and CE synced to EE, we don't
have failing builds.

See merge request !388

Fix a description for default scope on builds

Should be "**All* builds (from this project)" for the {project,admin}
builds page without scope.

Fix a regression on !2243 (#4240).

See merge request !4118

Add API endpoints for un/subscribing from/to a label



See merge request !4051

# Conflicts:
#	db/schema.rb

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

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

Closes #15638

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

These will fail until #558 is taken care of.

This allows us to display statistics in Grafana.

Update build log incrementally

Proof of concept implementation of incremental sending of build log to browser.

cc @jschatz1 @vsizov @grzesiek @tmaczukin 


See merge request !3737

Updated EE CHANGELOG for 8.7.5

See merge request !395

Updated CHANGELOG for 8.7.5

See merge request !4129

[ci skip]

Only show forks for users who can download code

The ForksController enforces this, so don't show the link if it won't go anywhere.

Closes #14272.

See merge request !4017

[ci skip]

and drop exception handling around HealthCheck::Utils.process_checks, it wasn't needed

Reuse runners edit form in admin and project area

Reuse runners edit form in admin and project area.

![reuse_runner_form](/uploads/d16e3ee196151b68f584d947f38a7c29/reuse_runner_form.png)

See merge request !4094

Removed tracking of total method execution times

See #17239 and 945c5b3f for more details. The Grafana dashboards used to visualize performance data were updated a while ago to no longer display this data.

See merge request !4124

The ForksController enforces this, so don't show the link if it won't go
anywhere.

Fix skipping pages when restoring backups

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/407

See merge request !375

Group commits by date in server timezone

`Time#to_date` just takes the (timezone-less) year, date, and month, and
creates a new date from that. Because the commits in the list are
grouped by date, rather than chunked when the date changes, a commit can
be shown in the wrong order if its CommitDate has a timezone-less date
that's different to other commits around it.

Convert all CommitDates to the server timezone before grouping, as that
will at least produce consistent results. Users can still see a
timestamp on the commit that doesn't match the date it's grouped under,
because the timestamp shown uses the user's local timezone, and the
grouping uses the server's timezone, but that was an issue anyway.

### Before
![image](/uploads/1ffe0e2f86e03590cb96126d4f340436/image.png)

### After
![image](/uploads/b1be1b08782385d13c56528242a5829b/image.png)

Closes #3870 and closes #17300.

See merge request !4052