Return 202 with JSON body on async removals on V4 API
What does this MR do?
Basically return 202 and proper JSON on async removals on:
- Changelog entry added
- Documentation created/updated
- API support added
- Added for this feature/bug
- All builds are passing
- Conform by the merge request performance guides
- Conform by the style guides
Branch has no merge conflicts with
master(if it does - rebase it please)
- Squashed related commits together
What are the relevant issue numbers?
Closes #3874 (closed)