Convert include guard to pragma once (#8957)

streaming/src/queue/transport.h

@@ -1,5 +1,4 @@
-#ifndef _STREAMING_QUEUE_TRANSPORT_H_
-#define _STREAMING_QUEUE_TRANSPORT_H_
+#pragma once
 
 #include "ray/common/id.h"
 #include "ray/core_worker/core_worker.h"
@@ -66,4 +65,3 @@ class Transport {
 };
 }  // namespace streaming
 }  // namespace ray
-#endif