[Test] Batch Invariant: Rename and organize tests (#27421)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

tests/v1/determinism/conftest.py

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def enable_batch_invariant_mode(monkeypatch: pytest.MonkeyPatch):
+    """Automatically enable batch invariant kernel overrides for all tests."""
+    monkeypatch.setenv("VLLM_BATCH_INVARIANT", "1")
+    yield