[core][rdt] Fix flaky send fail gloo test (#58924)

Signed-off-by: dayshah <dhyey2019@gmail.com>

Author: dayshah

python/ray/tests/gpu_objects/test_gpu_objects_gloo.py

@@ -69,6 +69,7 @@ def send(self, tensor):
     def recv(self, tensor):
         return tensor
 
+    @ray.method(concurrency_group="_ray_system")
     def clear_gpu_object_store(self):
         gpu_object_store = (
             ray._private.worker.global_worker.gpu_object_manager.gpu_object_store