Don't deploy git panel when opening the diff view (#25611)

Release Notes:

- N/A

crates/git_ui/src/project_diff.rs

@@ -78,7 +78,6 @@ impl ProjectDiff {
         window: &mut Window,
         cx: &mut Context<Workspace>,
     ) {
-        workspace.open_panel::<GitPanel>(window, cx);
         Self::deploy_at(workspace, None, window, cx)
     }