Fix namespace move callback behavior, especially to fix Geo replication of namespace moves during certain exceptions

What does this MR do?

Fix namespace move callback behavior, especially to fix Geo replication of namespace moves during certain exceptions.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

https://gitlab.com/gitlab-org/gitlab-ee/issues/6252

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a Backend maintainer
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/6252