[CI][AMD]BugFix] Fix deadlock occuring in test_moe_layer (vllm-project#40767)

Signed-off-by: Randall Smith <Randall.Smith@amd.com>

Author: rasmith

tests/kernels/moe/test_moe_layer.py

@@ -1632,6 +1632,7 @@ def _parallel_worker(
                 if all2all_manager is not None:
                     all2all_manager.destroy()
             total = total + 1
+            torch.distributed.barrier()
 
     skipped = total - (passed + failed)