Improve support for external issue references

Closes #33679, #34076, and #34082

See merge request !12485

Remove placeholder note when award emoji slash command is applied

Closes #34470

See merge request !12545

[ci skip]

Resolve "More actions dropdown hidden by end of diff"

Closes #33861

See merge request !12380

Only verifies top position after the request has finished to account for errors

See merge request !12559

Cleanup codeclimate.json file generated by CI

See merge request !12565

Fix 'New merge request' button for users who don't have push access to canonical project

See merge request !12560

Merge branch '34502-gitlab-git-hook-should-set-the-gl_repository-environment-variable' into 'master'

Set the GL_REPOSITORY env variable on Gitlab::Git::Hook

Closes #34502

See merge request !12572

updated version of issues baord images (doc)

See merge request !12558

Render add-diff-note with server and optimize styles

See merge request !12103

Fixed sidebar not collapsing on merge request in mobile screens

Closes #32759

See merge request !12489

Backport changes to Projects::IssuesController and the search bar

See merge request !12551

bugfix: use `require_dependency` to bring in DeclarativePolicy

Closes #34532

See merge request !12571

Resolve "Select branch dropdown is too close to branch name"

Closes #34349

See merge request !12515

Perform unzip quietly in UpdatePagesService

Closes gitlab-ee#225

See merge request !12539

Fixed new navgiation bar logo height in Safari

See merge request !12563

Fix scroll flicker

Closes #34407

See merge request !12501

Defer project destroys within a namespace in Groups::DestroyService#async_execute

See merge request !12435

Clean up issuable lists

Closes #26818

See merge request !11991

Supplement Traditional Chinese in Taiwan translation of Project Page & Repository Page

Closes #33443

See merge request !12514

This commit moves the rendering of the button back to the server, and
shows/hides it using opacity rather than display. It also removes the
transform applied to the button on hover (scale). Previously, both of these
factors automatically triggered a reflow, which creates a performance
bottleneck on pages with larger DOM size.

MR: !12103

Allow the feature flags to be enabled/disabled with more granularity

Closes #34078

See merge request !12357

Group#destroy would actually hard-delete all associated projects even
though the acts_as_paranoia gem is used, preventing Projects::DestroyService
from doing any work.

We first noticed this while trying to log all projects deletion to the Geo
log.

Merge branch '34403-issue-dropdown-persists-when-adding-issue-number-to-issue-description' into 'master'

Resolve "Issue dropdown persists when adding issue number to issue description"

Closes #34403

See merge request !12521

Run mysql tests on stable preperation branches like 9-3-stable-patch-2

See merge request !12552