[V0 Deprecation] Remove VLLM_USE_V1 from tests (#26341)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/v1/e2e/test_min_tokens.py

@@ -13,7 +13,6 @@ Covers:
 5) Multiple stop conditions
 """
 
-import os
 from typing import Optional, Union
 
 import pytest
@@ -161,9 +160,6 @@ MIN_TOKENS_TEST_CASES = [
 @pytest.fixture(scope="module")
 def llm_v1():
     """Create V1 LLM instance for testing"""
-    # Ensure V1 engine is used
-    os.environ["VLLM_USE_V1"] = "1"
-
     llm = LLM(
         model=TEST_MODEL,
         tensor_parallel_size=1,
@@ -503,6 +499,6 @@ if __name__ == "__main__":
     
     Usage:
         cd vllm/
-        VLLM_USE_V1=1 python -m pytest tests/v1/e2e/test_min_tokens.py -v
+        python -m pytest tests/v1/e2e/test_min_tokens.py -v
     """
     pytest.main([__file__, "-v"])