[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/cache/test_seacache.py

@@ -9,8 +9,8 @@ from types import SimpleNamespace
 
 import pytest
 import torch
+from vllm.utils.network_utils import get_file_store_init_method
 
-from tests.helpers.runtime import get_distributed_init_method
 from vllm_omni.diffusion.cache.seacache import (
     SeaCacheBackend,
     SeaCacheConfig,
@@ -375,7 +375,7 @@ def test_parameter_sharded_hook_handles_uneven_cfg_branch_dispatch() -> None:
     result_queue = manager.Queue()
     torch.multiprocessing.spawn(
         _uneven_cfg_sharded_worker,
-        args=(get_distributed_init_method("seacache_uneven_cfg_"), result_queue),
+        args=(get_file_store_init_method(), result_queue),
         nprocs=4,
     )
 
@@ -452,7 +452,7 @@ def test_hook_synchronizes_full_hybrid_sequence_parallel_group() -> None:
     result_queue = manager.Queue()
     torch.multiprocessing.spawn(
         _hybrid_sp_worker,
-        args=(get_distributed_init_method("seacache_hybrid_sp_"), result_queue),
+        args=(get_file_store_init_method(), result_queue),
         nprocs=4,
     )