collab: Remove `GET /contributor` endpoint (#46415)

This PR removes the `GET /contributor` endpoint from Collab, as it has
been moved to Cloud.

Release Notes:

- N/A
32af786a70Marshall Bowers committed on 1/9/2026, 2:39:19 AM· committed by GitHubparent0e97c18
3 files changedLine totals unavailable