assistant2: Fail find-replace tool if both strings are equal (#27783)

Models seem to do this ever so often and get very confused. Failing here
helps them recover.

Release Notes:

- N/A

Co-authored-by: Richard Feldman <richard@zed.dev>
e6c64ebf7eAgus Zubiaga committed on 3/31/2025, 2:23:46 PM· committed by GitHubparent12c58d0
2 files changedLine totals unavailable