[MISC] Consolidate cleanup() and refactor offline_inference_with_prefix.py (#9510)

tests/core/block/e2e/conftest.py

@@ -3,10 +3,9 @@ from typing import Callable, Iterable, Optional
 import pytest
 
 from vllm import LLM
+from vllm.distributed import cleanup_dist_env_and_memory
 from vllm.model_executor.utils import set_random_seed
 
-from ....conftest import cleanup
-
 
 @pytest.fixture
 def baseline_llm_generator(common_llm_kwargs, per_test_common_llm_kwargs,
@@ -37,7 +36,7 @@ def create_llm_generator(common_llm_kwargs, per_test_common_llm_kwargs,
 
         yield llm
         del llm
-        cleanup()
+        cleanup_dist_env_and_memory()
 
     for llm in generator_inner():
         yield llm