This is a first iteration to address the following issue:
https://gitlab.com/gitlab-org/quality/team-tasks/issues/168

Note: depends on
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/30945

Refactor collapse issue comments end-to-end test

See merge request gitlab-org/gitlab-ce!30902

Refactor create issue end-to-end test

See merge request gitlab-org/gitlab-ce!30945

Fixes typo in developer documentation

See merge request gitlab-org/gitlab-ce!30964

Fix the project auto devops API

See merge request gitlab-org/gitlab-ce!30946

If `project_auto_devops.enabled` is nil for a project, when setting any
auto devops values via the API, we try to create a new row in the DB,
instead of re-using the existing one. This leads to the project_id
being set to nil, and the database `NOT NULL` constraint leading to a
500 response.

This commit resolves the issue by correctly detecting the presence of a
ProjectAutoDevops row and re-using it. Persistence is also moved away
from explicit `update!` calls and into relying on `autosave: true` on
the model.

Fix Gitaly auto-detection caching

Closes #64802

See merge request gitlab-org/gitlab-ce!30954

Remove duplicate buttons

Closes #64160

See merge request gitlab-org/gitlab-ce!30757

Document database review process

See merge request gitlab-org/gitlab-ce!30405

See https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/6069

Get rid of `worker_label` in RubySampler

See merge request gitlab-org/gitlab-ce!30942

Avoid increasing redis counters when usage_ping is disabled

See merge request gitlab-org/gitlab-ce!30949

If `GitalyClient#can_use_disk?` returned `false`, it was never cached
properly and led to excessive number of Gitaly calls. Instead of using
`cached_value.present?`, we need to check `cached_value.nil?`.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/64802

Fixes the alignment on reports

See merge request gitlab-org/gitlab-ce!30839

- Removes a justify-center class that causes reports to centrally align

Centers loading icon in CI action

Closes #64265

See merge request gitlab-org/gitlab-ce!30947

Use `issuable_path` helper

See merge request gitlab-org/gitlab-ce!30913

Resolve "Export frontend fixtures as pipeline artifact"

Closes #64722 and #59166

See merge request gitlab-org/gitlab-ce!30917

This refactor:
- Moves the tests pre-conditions to a before blocks
- Creates an issue via the api for the second test to improve the
test suite performance

We have Prometheus::PidProvider which sets correct worker id for a
process, so such implementation of `worker_label` in the sampler is
obsolete.

Fix regression in re-naming files

Closes #64784

See merge request gitlab-org/gitlab-ce!30941

Adjust redis cache metrics

See merge request gitlab-org/gitlab-ce!30572

* Remove `controller` and `action` labels from duration histogram.
* Create a new simple counter for `controller` and `action`.
* Adjust histogram buckets to observe smaller response times.

Better scope end-to-end test

See merge request gitlab-org/gitlab-ce!30897

Better scope another end-to-end test

See merge request gitlab-org/gitlab-ce!30896

To:
- Better separate scopes (pre-conditions on before, tests on it)
- Remove unnecessary expectation
- Replace other unnecessary expectations by page.assert_text
- Move variables closer to where they're used

Quarantine failing "rebase_merge_request_spec.rb"

See merge request gitlab-org/gitlab-ce!30933

Web IDE Usage Ping for Create SMAU

Closes #63886

See merge request gitlab-org/gitlab-ce!30800

The actions tracked in the web IDE are:
- creation of commits
- creation of merge requests
- projects loaded

Better scope end-to-end test

See merge request gitlab-org/gitlab-ce!30895

Add a note about private_profile changes in 12.1

Closes #64613

See merge request gitlab-org/gitlab-ce!30772

Documentations for parallel execution strategy for Merge Trains

Closes #63369

See merge request gitlab-org/gitlab-ce!30661

This commit adds a documentation for parallel pipelines on merge
trains.

Fix typo

Add endsWith to polyfill

See merge request gitlab-org/gitlab-ce!30920