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

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

Closes #15638

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 CHANGELOG for 8.7.5

See merge request !4129

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.

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

Update cas.md to reflect the current syntax, and added that gitlab-ctl reconfigure should be run.

I spent a while trying to figure our why the cas wasn't working!

Someone may need to update the source code section of the wiki

See merge request !3850

Because method call timings are inclusive (that is, they include the
time of any sub method calls) this would lead to the total method
execution time often being far greater than the total transaction time.
Because this is incredibly confusing it's best to simply _not_ track the
total method execution time, after all it's not that useful to begin
with.

Fixes gitlab-org/gitlab-ce#17239

This reverts commit 075ace5686c63d40f7e9fa02bf37e1bd3168f7e7.

This reverts commit 7b295370efc124360d52e37e8e709914028f6443.

delete the enabled_oauth_sign_in_sources after getting it's value into enabled_oauth_sign_in_sources

just delete enabled_oauth_sign_in_sources and get it's value

Revert "disabled_oauth_sign_in_sources column" and keep on schema only the disabled_oauth_sign_in_sources column

This reverts commit 95358e0095403ad44149d11922d52e4590285a20.

This reverts commit 78a832d0fd7ff445c707809134dbb2a42d2a9e03.

Show help only for the enabled OAuth Providers on oauth-providers-help block

aria: { describedby: help_block_id } instead of 'aria-describedby' => help_block_id

provider and not p

a more simple approach to the OmniAuth helper links for oauth-providers-help