Use message body for merge request description

Closes #40968

See merge request gitlab-org/gitlab-ce!15839

Merge branch '41041-undefined-method-new_project_guidelines_html-unable-to-load-from-cache' into 'master'

Resolve "undefined method `new_project_guidelines_html', unable to load from cache"

Closes #41041

See merge request gitlab-org/gitlab-ce!15878

Clears the current Appearance cache otherwise it breaks since new_project_guidelines_html would be missing

Solves https://gitlab.com/gitlab-org/gitlab-ce/issues/41041.
Signed-off-by: Rémy Coutable <remy@rymai.me>

Add js prefix for issuable-edit

Closes #40965

See merge request gitlab-org/gitlab-ce!15813

Stop "ERROR: TypeError{}" from being logged to the console and fail tests

Closes #37619

See merge request gitlab-org/gitlab-ce!15830

Updated image for diff navigation docs

See merge request gitlab-org/gitlab-ce!15875

Use app host instead of asset host when rendering image blob or diff

Closes #41002

See merge request gitlab-org/gitlab-ce!15854

Merge branch '41023-activerecord-staleobjecterror--attempted-to-update-a-stale-object--ci-build' into 'master'

Job dropping by MissingDependenciesError should consider StaleObjectError

Closes #41023

See merge request gitlab-org/gitlab-ce!15873

Checks for null in job tooltip title

Closes #40997

See merge request gitlab-org/gitlab-ce!15869

Milestone sidebar docs

See merge request gitlab-org/gitlab-ce!15861

Fix migration that removes issues.branch_name

See merge request gitlab-org/gitlab-ce!15858

Clarify casing of I18N placeholder names

See merge request gitlab-org/gitlab-ce!15867

Fix comment on image discussion icon alignment (update icons)

Closes #39608

See merge request gitlab-org/gitlab-ce!15760

rename remaining issue_ prefixed files

See merge request gitlab-org/gitlab-ce!15818

Ignore temporary table in schema

Closes #40976

See merge request gitlab-org/gitlab-ce!15866

Gitaly mirroring migration prep

Closes gitaly#816

See merge request gitlab-org/gitlab-ce!15775

Backport epic in issue

See merge request gitlab-org/gitlab-ce!15799

fixes some markup issues in the js style guide docs

See merge request gitlab-org/gitlab-ce!15828

Moved URL utility methods into exported es modules

See merge request gitlab-org/gitlab-ce!15783

Animate contextual sidebar; change class names for easier readability

Closes #35724

See merge request gitlab-org/gitlab-ce!15797

Docs: add index for `doc/administration/operations/`

See merge request gitlab-org/gitlab-ce!15852

Add cop for use of remove_column

See merge request gitlab-org/gitlab-ce!15855

small change to make less conflict with EE version

See merge request gitlab-org/gitlab-ce!15809