fix: RabbitBroker's ping is more objective

faststream/rabbit/broker/broker.py

@@ -839,7 +839,7 @@ async def ping(self, timeout: Optional[float]) -> bool:
                 if cancel_scope.cancel_called:
                     return False
 
-                if not self._connection.is_closed:
+                if self._connection.connected.is_set():
                     return True
 
                 await anyio.sleep(sleep_time)