[BUG] test_internode hangs and times out on repeated runs

When test_internode is run in a tight loop for stress testing, it randomly hangs and eventually times out.
It seems to be related to TMA function.

Screenshot of the hang:

### Environment
- Commit Hash: The latest commit on main (e3908bf5bd0cc6265bcb225d15cd8c996d4759ef)
- Hardware: Reproducible on both 2/4-node H20 and 2/4-node H200 setups. ConnectX-7 with dual port 200G. RoCEv2 with PFC.
- Image: ngc 24.02
- Driver / CUDA Version: <570.148.08 / 12.8>

### Steps to Reproduce
I modified the test script for stress testing.

https://github.com/deepseek-ai/DeepEP/blob/e3908bf5bd0cc6265bcb225d15cd8c996d4759ef/tests/test_internode.py#L174-L176
Adding a return to skip performance test.
```python
if local_rank == 0:
print('', flush=True)
return
```
https://github.com/deepseek-ai/DeepEP/blob/e3908bf5bd0cc6265bcb225d15cd8c996d4759ef/tests/test_internode.py#L242-L245
Running continuously for multiple rounds.
```python
for i in range(10000):
test_main(args, num_sms, local_rank, num_local_ranks, num_ranks, num_nodes, rank, buffer, group)
if local_rank == 0:
print('', flush=True)
```

Moving torch.manual_seed(rank) inside the loop to ensure identical inputs for each iteration does not fix the issue.
I changed 'assert' to 'print' to prevent interrupting the testing program, but it still hang then timeout. calc_diff and check_data will get inf or nan.

Last Known Good Commit: 7705f53 (The stress test passes reliably on this commit). This is the last commit before the internode TMA feature was merged.
First Known Bad Commit: a2fa3b7 (The stress test fails on this commit). This is the first commit that introduces the internode TMA functionality.