[Offload][L0] clear completed events from a wait list (#186379)

Queue's WaitEvent collection wasn't being cleared after synchronization
and resetting of the events. This led to hangs on subsequent host
synchronizations if not preceeded by any other operation.

offload/plugins-nextgen/level_zero/src/L0Device.cpp

@@ -319,6 +319,9 @@ Error L0DeviceTy::synchronizeImpl(__tgt_async_info &AsyncInfo,
           return Err;
       }
     }
+    // In either case, all the events are now reset and released
+    // back into the pool. We need to clear them from the queue.
+    AsyncQueue->WaitEvents.clear();
   }
 
   // Commit delayed USM2M copies.