git_ui: Try to prompt the model out of including the diff output (#26281)

This PR updates the prompt for generating commit messages to tell the
model not to include the raw diff output in the message.

Release Notes:

- N/A
ed417da536Marshall Bowers committed on 3/7/2025, 3:05:35 PM· committed by GitHubparentd1c6789
1 file changedLine totals unavailable