Temporarily revert git panel diff editor feature (#22733)

The existing code was causing us to constantly re-scan files when
anything changed in the project. Temporarily revert this as we're about
to rework this entire UI with the new primitives.

follow up to https://github.com/zed-industries/zed/pull/22329

Release Notes:

- N/A

---------

Co-authored-by: Cole <cole@zed.dev>

crates/project/src/lsp_store.rs

@@ -3108,7 +3108,6 @@ impl LspStore {
             WorktreeStoreEvent::WorktreeUpdateSent(worktree) => {
                 worktree.update(cx, |worktree, _cx| self.send_diagnostic_summaries(worktree));
             }
-            WorktreeStoreEvent::GitRepositoryUpdated => {}
         }
     }