Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7237#note_21626953
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7237#note_21626952

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7237#note_21626434

* upstream/master: (1122 commits)
  Update CHANGELOG.md for 8.16.2
  Display project ID in project settings (!8572)
  fixed points from comments to improve code quality
  Update CHANGELOG.md for 8.14.8
  Statisfy eslint
  Add CHANGELOG entry
  Fix access to the wiki code via HTTP when repository feature disabled
  Display fullscreen button on small screens (!5302)
  Prevent removing fields from dropdowns on input elements
  fix for all themes
  Return struct instead of multiple values
  Fix race conditions for AuthorizedProjectsWorker
  Add User#nested_groups and User#nested_projects methods
  Fix spec failure due to timestamp ordering issue in mySQL
  Fixed error with filter keyboard tests
  `can?` already includes the `feature_available?` check
  Test there is no Merge Request button when MRs are disabled
  Ensure the correct Merge Request button is found
  Add 409 conflict tests
  Add CHANGELOG
  ...

[ci skip]

Resolve "regression in commit title bar"

Closes #27013

See merge request !8751

Resolve "Branch index delete button inconsistently spaced and misaligned"

Closes #24895

See merge request !8646

Display project ID

Closes #18350

See merge request !8572

Fix access to the wiki code via HTTP when repository feature disabled

Closes #26518

See merge request !8758

Copying a rendered issue/comment will paste into GFM textareas as actual GFM

See merge request !8597

Color + and - signs in diffs to increase code legibility

Closes #26186

See merge request !8768

Resolve "Line numbers now in copy pasta data"

Closes #27021

See merge request !8706

Fix race conditions for AuthorizedProjectsWorker

Closes #26194 and #26310

See merge request !8701

[ci skip]

Fixed label select toggle not updating correctly

Closes #26119

See merge request !8601

Fix autocomplete initial undefined state (loading)

Closes #26775

See merge request !8667

Prevent removal of input that is the parent dropdown element

Closes #25312

See merge request !8397

Fix CI requests concurrency

See merge request !8760

Backport changes introduced by https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1078

See merge request !8657

# Conflicts:
#	app/assets/javascripts/lib/utils/common_utils.js.es6

Fix mini-pipeline stage tooltip text wrapping

Closes #27014

See merge request !8771

Display fullscreen button on small screens

Closes #19891

See merge request !5302

EE backport for new application settings update service

See merge request !8665

Fix spec failure due to timestamp ordering issue in mySQL

Closes #26622

See merge request !8778

Fix 500 error for Group#web_url method if nested group

See merge request !8743

Nested groups feature improvemetns

See merge request !8448

Update enviroments.md - example CURL requests had a typo in the URL

See merge request cd ../gdk-ee/

Enable HAML-LINT linters phase 2

Closes #22072

See merge request !8566

There were two cases that could be problematic:

1. Because sometimes AuthorizedProjectsWorker would be scheduled in a
   transaction it was possible for a job to run/complete before a
   COMMIT; resulting in it either producing an error, or producing no
   new data.

2. When scheduling jobs the code would not wait until completion. This
   could lead to a user creating a project and then immediately trying
   to push to it. Usually this will work fine, but given enough load it
   might take a few seconds before a user has access.

The first one is problematic, the second one is mostly just annoying
(but annoying enough to warrant a solution).

This commit changes two things to deal with this:

1. Sidekiq scheduling now takes places after a COMMIT, this is ensured
   by scheduling using Rails' after_commit hook instead of doing so in
   an arbitrary method.

2. When scheduling jobs the calling thread now waits for all jobs to
   complete.

Solution 2 requires tracking of job completions. Sidekiq provides a way
to find a job by its ID, but this involves scanning over the entire
queue; something that is very in-efficient for large queues. As such a
more efficient solution is necessary. There are two main Gems that can
do this in a more efficient manner:

* sidekiq-status
* sidekiq_status

No, this is not a joke. Both Gems do a similar thing (but slightly
different), and the only difference in their name is a dash vs an
underscore. Both Gems however provide far more than just checking if a
job has been completed, and both have their problems. sidekiq-status
does not appear to be actively maintained, with the last release being
in 2015. It also has some issues during testing as API calls are not
stubbed in any way. sidekiq_status on the other hand does not appear to
be very popular, and introduces a similar amount of code.

Because of this I opted to write a simple home grown solution. After
all, all we need is storing a job ID somewhere so we can efficiently
look it up; we don't need extra web UIs (as provided by sidekiq-status)
or complex APIs to update progress, etc.

This is where Gitlab::SidekiqStatus comes in handy. This namespace
contains some code used for tracking, removing, and looking up job IDs;
all without having to scan over an entire queue. Data is removed
explicitly, but also expires automatically just in case.

Using this API we can now schedule jobs in a fork-join like manner: we
schedule the jobs in Sidekiq, process them in parallel, then wait for
completion. By using Sidekiq we can leverage all the benefits such as
being able to scale across multiple cores and hosts, retrying failed
jobs, etc.

The one downside is that we need to make sure we can deal with
unexpected increases in job processing timings. To deal with this the
class Gitlab::JobWaiter (used for waiting for jobs to complete) will
only wait a number of seconds (30 by default). Once this timeout is
reached it will simply return.

For GitLab.com almost all AuthorizedProjectWorker jobs complete in
seconds, only very rarely do we spike to job timings of around a minute.
These in turn seem to be the result of external factors (e.g. deploys),
in which case a user is most likely not able to use the system anyway.

In short, this new solution should ensure that jobs are processed
properly and that in almost all cases a user has access to their
resources whenever they need to have access.

Fixed error with filter keyboard tests

See merge request !8777

Only show Merge Request button when user can create a MR

See merge request !8639