Fix Mermaid drawings not loading on some browsers

Closes #42052

See merge request gitlab-org/gitlab-ce!16537

System hooks for Merge Requests

See merge request gitlab-org/gitlab-ce!14387

Fix the user-agent detail API endpoint for project snippets

Closes #42129

See merge request gitlab-org/gitlab-ce!16521

Add modal for stopping jobs in admin area

Closes #41305

See merge request gitlab-org/gitlab-ce!16283

Update ConvDev Index docs w better screenshot

See merge request gitlab-org/gitlab-ce!16533

Add openSUSE to the supported Unix OS list

See merge request gitlab-org/gitlab-ce!16544

Remove a broken link in the docs

See merge request gitlab-org/gitlab-ce!16532

Add the :migration metadata, and don't use factories in FixWronglyRenamedRoutes spec

See merge request gitlab-org/gitlab-ce!16535

Resolve "Cannot filter issues by labels ending with a plus char in board view"

Closes #41715 and #34252

See merge request gitlab-org/gitlab-ce!16490

As mentioned in https://github.com/knsv/mermaid/issues/291#issuecomment-287673609, the
parameter should be `startOnLoad` instead of `loadOnStart`. In addition, `mermaid.initialize()`
expects to see `startOnLoad` in the `mermaid` hash:

https://github.com/knsv/mermaid/blob/6cd5ffe637d88525b93417bf3954e9c0e5a4deb8/src/mermaid.js#L118

Closes #42052

Remove unused CSS selectors for Cycle Analytics (between 1st iteration and 2nd iteration)

Closes #41743

See merge request gitlab-org/gitlab-ce!16270

Double padding for file-content wiki class on larger screens

See merge request gitlab-org/gitlab-ce!16534

Filter groups and projects dropdowns of search page on backend

Closes #38739

See merge request gitlab-org/gitlab-ce!16336

Signed-off-by: Rémy Coutable <remy@rymai.me>

https://gitlab.com/gitlab-org/gitlab-ce/issues/34252

Fix bug in security release with deploy keys migration

See merge request gitlab-org/gitlab-ce!16531

Further simplify app/views/projects/buttons/_dropdown.html.haml

See merge request gitlab-org/gitlab-ce!16503

Backport 10.3.4 security fixes into master

See merge request gitlab-org/gitlab-ce!16509

Open visibility help in new tab

Closes #39591

See merge request gitlab-org/gitlab-ce!16268

Resolve "Closed issue label in todo's styling is difficult to read"

Closes #41874

See merge request gitlab-org/gitlab-ce!16414

Resolve "Allow toggling of performance bar in development"

Closes #42006

See merge request gitlab-org/gitlab-ce!16495

Revert "Merge branch 'pre-commit-prettier' into 'master'"

See merge request gitlab-org/gitlab-ce!16217

The performance bar is still displayed by default in development.
Signed-off-by: Rémy Coutable <remy@rymai.me>