git_ui: Remove unused ProjectDiffEmptyState component (#51436)

Just cleaning up our component set a bit. This one wasn't used at all.

Release Notes:

- N/A
d4bb640555Danilo Leal committed on 3/13/2026, 12:09:53 AM· committed by GitHubparentb15a8c1
1 file changedLine totals unavailable