collab: Remove `POST /billing/subscriptions/sync` endpoint (#35232)

This PR removes the `POST /billing/subscriptions/sync` endpoint, as it
has been moved to `cloud.zed.dev`.

Release Notes:

- N/A
ab90ed41daMarshall Bowers committed on 7/28/2025, 8:22:54 PM· committed by GitHubparent994d400
2 files changedLine totals unavailable