test: update test based on review

Author: KowalskiThomas

Lib/test/test_bytes.py

@@ -2908,6 +2908,9 @@ def check(funcs, it):
             check([iter_next] + [iter_reduce] * 10, iter(ba))  # for tsan
             check([iter_next] + [iter_setstate] * 10, iter(ba))  # for tsan
 
+    @unittest.skipUnless(support.Py_GIL_DISABLED, 'this test can only possibly fail with GIL disabled')
+    @threading_helper.reap_threads
+    @threading_helper.requires_working_threading()
     def test_free_threading_bytearray_resize(self):
         def resize_stress(ba):
             for _ in range(100_000):
@@ -2919,8 +2922,8 @@ def resize_stress(ba):
 
         ba = bytearray(100)
         threads = [threading.Thread(target=resize_stress, args=(ba,)) for _ in range(4)]
-        for t in threads: t.start()
-        for t in threads: t.join()
+        with threading_helper.start_threads(threads):
+            pass
 
 if __name__ == "__main__":
     unittest.main()