[CI/UT][Graph] Add ut for torchair graph mode (#1103)

### What this PR does / why we need it?
Add ut for torchair graph mode on DeepSeekV3

### How was this patch tested?
CI passed with new added test.

---------

Signed-off-by: MengqingCao <cmq0113@163.com>
Signed-off-by: Mengqing Cao <cmq0113@163.com>

tests/conftest.py

@@ -17,6 +17,7 @@
 # Adapted from vllm-project/vllm/blob/main/tests/conftest.py
 #
 
+import contextlib
 import gc
 from typing import List, Optional, Tuple, TypeVar, Union
 
@@ -53,11 +54,17 @@ PromptAudioInput = _PromptMultiModalInput[Tuple[np.ndarray, int]]
 PromptVideoInput = _PromptMultiModalInput[np.ndarray]
 
 
-def cleanup_dist_env_and_memory():
+def cleanup_dist_env_and_memory(shutdown_ray: bool = False):
     destroy_model_parallel()
     destroy_distributed_environment()
+    with contextlib.suppress(AssertionError):
+        torch.distributed.destroy_process_group()
+    if shutdown_ray:
+        import ray  # Lazy import Ray
+        ray.shutdown()
     gc.collect()
     torch.npu.empty_cache()
+    torch.npu.reset_peak_memory_stats()
 
 
 class VllmRunner: