[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/distributed/kv_transfer/test_simple_pipe.py

@@ -1,12 +1,12 @@
-import unittest
 from unittest.mock import MagicMock, patch
 
 import torch
 
+from tests.ut.base import TestBase
 from vllm_ascend.distributed.kv_transfer.simple_pipe import SimplePipe
 
 
-class TestSimplePipe(unittest.TestCase):
+class TestSimplePipe(TestBase):
 
     @classmethod
     def _create_mock_config(self):