git_ui: Update section header checkboxes immediately on stage/unstage all (#57148)

Release Notes:

- Fixed Stash All / Unstash All checkbox UI delay issue

---------

Signed-off-by: Xiaobo Liu <cppcoffee@gmail.com>

crates/git_ui/src/git_panel.rs

@@ -1743,17 +1743,14 @@ impl GitPanel {
         cx.spawn({
             async move |this, cx| {
                 let result = this
-                    .update(cx, |this, cx| {
-                        let task = active_repository.update(cx, |repo, cx| {
+                    .update(cx, |_this, cx| {
+                        active_repository.update(cx, |repo, cx| {
                             if stage {
                                 repo.stage_all(cx)
                             } else {
                                 repo.unstage_all(cx)
                             }
-                        });
-                        this.update_counts(active_repository.read(cx));
-                        cx.notify();
-                        task
+                        })
                     })?
                     .await;
 
@@ -1761,6 +1758,7 @@ impl GitPanel {
                     if let Err(err) = result {
                         this.show_error_toast(if stage { "add" } else { "reset" }, err, cx);
                     }
+                    this.update_counts(active_repository.read(cx));
                     cx.notify()
                 })
             }