collab: Remove stray `dev_servers.rs` module (#55566)

This PR removes a stray, empty `dev_servers.rs` module from the `collab`
crate.

Release Notes:

- N/A
c5599efaaaMarshall Bowers committed on 5/3/2026, 4:45:40 PM· committed by GitHubparenta593270
1 file changedLine totals unavailable