[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_buffer.py

@@ -1,9 +1,9 @@
-import unittest
 import zlib
 from unittest.mock import MagicMock
 
 import torch
 
+from tests.ut.base import TestBase
 from vllm_ascend.distributed.kv_transfer.simple_buffer import (SimpleBuffer,
                                                                int32_hash)
 
@@ -17,7 +17,7 @@ class MockSimplePipe:
         self.deallocate_buffer = MagicMock()
 
 
-class TestSimpleBuffer(unittest.TestCase):
+class TestSimpleBuffer(TestBase):
 
     def setUp(self):
         self.pipe = MockSimplePipe()