Fix export removal for hashed-storage projects within a renamed or deleted namespace

What does this MR do?

When a namespace is renamed or deleted, all exports for projects within that namespace are invalidated. However, when hashed storage is enabled, the exports are not removed. This MR restores the correct behaviour when hashed storage is enabled.

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

We don't currently invalidate project exports when a project is renamed, but since this is the same between hashed and legacy storage, I'm happy to leave it untouched.

Why was this MR needed?

Fix a bug when hashed storage is enabled

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes #42270 (closed)