WIP: Resolve "Some projects have a non-working comment area for merge requests"

What does this MR do?

EE version of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24307

🍒 cherry-pick missed-deliverable MRs into 11-7-stable-ee

• https://gitlab.com/gitlab-org/gitlab-ee/commit/3448f221e9d41a9e1884fd843d11e1e42f8afa0b
• https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9092
• https://gitlab.com/gitlab-org/gitlab-ee/commit/8a7f40b1e2719fec7d666cc1b7193a705c7b7faf
• https://gitlab.com/gitlab-org/gitlab-ee/commit/c4798ba6ef419e94970fd34ac8ea52328bacffaa

Screenshots

/	FF error_tracking ✅	FF error_tracking 🚫
tracing ✅
tracing 🚫

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer

Closes #11 (closed)