Allow discover by userid - issue 28517

What does this MR do?

Modify the discover method in the internal API to find user by user_id in addition to current key_id.

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

Not that I'm aware of.

Why was this MR needed?

We use the GL_ID environment variable that is passed into the git hooks to identify the user. The GL_ID arrives as either key-id=# or user-id=#. The discover api only supports key-id.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

Discussed pipeline failure in issue with @DouweM. We have been using this patch in our instance for several months. We have patched each new upgrade of Gitlab.

• Changelog entry added, if necessary
• Documentation created/updated
• API support 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

What are the relevant issue numbers?

Closes #28517 (closed)