Remove more references to 'model' in GPUI APIs (#23693)

Release Notes:

- N/A

crates/worktree/src/worktree_tests.rs

@@ -1884,7 +1884,7 @@ async fn test_random_worktree_changes(cx: &mut TestAppContext, mut rng: StdRng)
 // all changes to the worktree's snapshot.
 fn check_worktree_change_events(tree: &mut Worktree, cx: &mut Context<Worktree>) {
     let mut entries = tree.entries(true, 0).cloned().collect::<Vec<_>>();
-    cx.subscribe(&cx.model(), move |tree, _, event, _| {
+    cx.subscribe(&cx.entity(), move |tree, _, event, _| {
         if let Event::UpdatedEntries(changes) = event {
             for (path, _, change_type) in changes.iter() {
                 let entry = tree.entry_for_path(path).cloned();