Fix error 500 renaming group. Also added specs and changelog. (!8201) · Merge requests · GitLab.org / GitLab FOSS · GitLab

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17922 and https://gitlab.com/gitlab-org/gitlab-ce/issues/23223

When there are tags in the container registry, the group removal is not allowed. We should gracefully recover from the error and notify the user.

Changelog entry added
Tests
- 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