[Test] Cleanup for helpers (#6523)

Signed-off-by: wangyu <410167048@qq.com>
Signed-off-by: [Your Name] <your.email@example.com>
Co-authored-by: amy-why-3459 <wuhaiyan17@huawei.com>

tests/helpers/__init__.py

@@ -1,6 +1,9 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+
 """Shared, importable test helper utilities.
 
-Submodules (``assertions``, ``env``, ``media``, ``runtime``, …) are imported
+Submodules (``assertions``, ``clean``, ``client``, ``media``, ``runtime``, …) are imported
 explicitly by callers. Unit tests for these helpers live under ``tests/``.
 Avoid star-importing everything here: that ran before refactor only inside the
 old monolithic ``conftest``; a greedy ``__init__`` changes import order and can