[Tests] Use get_file_store_init_method helper from vllm (#7528)

Signed-off-by: Nick Cao <ncao@redhat.com>
Co-authored-by: Codex <noreply@openai.com>

tests/diffusion/distributed/test_hsdp.py

@@ -9,8 +9,8 @@ import torch
 import torch.distributed as dist
 import torch.nn as nn
 from torch.distributed.tensor import DeviceMesh, DTensor
+from vllm.utils.network_utils import get_file_store_init_method
 
-from tests.helpers.runtime import get_distributed_init_method
 from vllm_omni.diffusion.data import DiffusionParallelConfig
 from vllm_omni.diffusion.distributed import hsdp as hsdp_module
 from vllm_omni.diffusion.distributed.hsdp import (
@@ -43,7 +43,7 @@ def cpu_process_group():
         yield
         return
 
-    dist.init_process_group("gloo", rank=0, world_size=1, init_method=get_distributed_init_method())
+    dist.init_process_group("gloo", rank=0, world_size=1, init_method=get_file_store_init_method())
     try:
         yield
     finally: