Refactor  Cluster docs

Closes #39952

See merge request gitlab-org/gitlab-ce!15418

Resolve "lock/confidential issuable sidebar custom svg icons iteration"

Closes #37508

See merge request gitlab-org/gitlab-ce!15372

Isolate the fork network background migrations

See merge request gitlab-org/gitlab-ce!15393

Cache the number of user SSH keys

See merge request gitlab-org/gitlab-ce!15401

When a custom header logo is present, don't show GitLab type logo

See merge request gitlab-org/gitlab-ce!15410

Make sure NotesActions#noteable returns a Noteable in the update action

Closes #40208

See merge request gitlab-org/gitlab-ce!15421

Update license_finder to 3.1.1

Closes #34955 et #40020

See merge request gitlab-org/gitlab-ce!15319

By caching the number of personal SSH keys we reduce the number of
queries necessary on pages such as ProjectsController#show (which can
end up querying this data multiple times).

The cache is refreshed/flushed whenever an SSH key is added, removed, or
when a user is removed.

Adjust openid_connect_spec to use `raise_error`

Closes #40093

See merge request gitlab-org/gitlab-ce!15420

Backport delete epic changes

Closes #40162

See merge request gitlab-org/gitlab-ce!15414

Change logic of repo name and slugs in docs review script

See merge request gitlab-org/gitlab-ce!15395

Use relative git object paths to construct absolute ones before setting Env

See merge request gitlab-org/gitlab-ce!15376

Using the `raise_error`-matcher instead of `throw_symbol` makes sure
our after blocks get called in the test suite.

Add basic docs for troubleshooting database problems

See merge request gitlab-org/gitlab-ce!15416

Add readme only default project view preference

See merge request gitlab-org/gitlab-ce!15415

Add an attributes bag class as a GitalyClient helper

See merge request gitlab-org/gitlab-ce!15346

Update container repository path reference

Closes #40199

See merge request gitlab-org/gitlab-ce!15417

Resolve "Clicking on GPG verification badge jumps to top of the page"

Closes #40198

See merge request gitlab-org/gitlab-ce!15407

We should allow to use double underscore in the path, and it seems that
our container repository path regexp was outdated.

See https://github.com/docker/distribution/blob/master/reference/regexp.go

Fix Typo in environment create definition

See merge request gitlab-org/gitlab-ce!15413

We need to make room for Runner and Omnibus docs.
This change makes sure the correct values are defined
based on CI_PROJECT_NAME.

The option to choose readme only as a users default project view was
restored in !14900

In the new navigation header, when a user uploads a custom header
logo GitLab will still show the 'GitLab' type logo. This is often
undesirable as the user may want to upload a logo with their own
name present. This change will toggle the GitLab type logo if a
custom header logo is present.

Resolve "Follow-up from "Enable multiple queries per Prometheus graph""

Closes #39861

See merge request gitlab-org/gitlab-ce!15363

Resolve "npm list errors for gitlab-svgs and node-pre-gyp"

Closes #40020

See merge request gitlab-org/gitlab-ce!15340