collab: Remove unused `RateLimiter` (#29343)

This PR removes the `RateLimiter` from the collab codebase, as it is no
longer used.

Release Notes:

- N/A
ea5ce2a1a4Marshall Bowers committed on 4/24/2025, 2:23:17 PM· committed by GitHubparentfd8eeb5
8 files changedLine totals unavailable