Remove `git_panel::GenerateCommitMessage` in favor of `git::GenerateCommitMessage` (#33421)

`git_panel::GenerateCommitMessage` has no handler,
`git::GenerateCommitMessage` should be preferred. Could add a
`#[action(deprecated_aliases = ["git_panel::GenerateCommitMessage"])]`,
but decided not to because that action didn't work. So instead uses of
it will show up as keymap errors.

Closes #32667

Release Notes:

- N/A
b1450b6d71Michael Sloan committed on 6/25/2025, 10:29:30 PM· committed by GitHubparent1af9f98
1 file changedLine totals unavailable