WIP: Object storage ee to ce backport

What does this MR do?

This is another take on https://gitlab.com/gitlab-org/gitlab-ce/issues/40781 and https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17358.

Does it work? I doubt, but I'm sure that I picked 95% of patches for OS support from EE.

The flow was boring but simple:

1. Start with a git checkout -b object-storage-ee-to-ce-backport $(git merge-base origin/master v9.4.0),
2. Look for CI oriented OS MRs here: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests?label_name%5B%5D=CI%2FCD&milestone_title=9.4&scope=all&state=merged
3. git cherry-pick <merge-commit> -m1 (in correct order, resolve conflicts)
4. Look for general OS MRs here (LFS / uploads / fixes / and so): https://gitlab.com/gitlab-org/gitlab-ee/merge_requests?milestone_title=9.4&scope=all&state=merged
5. git cherry-pick <merge-commit> -m1 (in correct order, resolve conflicts)
6. Then bump to next major version: git merge $(git merge-base origin/master v9.5.0) (resolve conflicts),
7. Go back to 2.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?