[FOLLOWUP] Use base test to avoid patch everwhere (#1634)

### What this PR does / why we need it?
Use base test to avoid patch everwhere.

Followup here: https://github.com/vllm-project/vllm-ascend/pull/1566

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
ut ci passed

- vLLM version: v0.9.2
- vLLM main:
8d0a01a5f2

Signed-off-by: Yikun Jiang <yikunkero@gmail.com>

tests/ut/test_utils.py

@@ -15,7 +15,6 @@
 
 import math
 import os
-import unittest
 from threading import Lock
 from unittest import mock
 
@@ -309,7 +308,7 @@ class TestUtils(TestBase):
         self.assertEqual(mock_customop.register_oot.call_count, 2)
 
 
-class TestProfileExecuteDuration(unittest.TestCase):
+class TestProfileExecuteDuration(TestBase):
 
     def setUp(self):
         utils.ProfileExecuteDuration._instance = None