[Misc] Move tensor schema tests (#22612)

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

tests/utils_/__init__.py

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+This module is named `utils_` instead of `utils` to avoid obscuring
+`tests/utils.py`.
+"""