[UT] Fix ut test (#4472)

### What this PR does / why we need it?

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

- vLLM version: v0.11.2
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.2

Signed-off-by: hfadzxy <starmoon_zhang@163.com>

tests/ut/attention/test_mla_v1.py

@@ -456,6 +456,8 @@ class TestAscendMLAMetadataBuilderBuild(TestBase):
     @patch("vllm_ascend.attention.mla_v1.get_ascend_config")
     def test_build_prefix_no_cache_metadata(self, mock_get_ascend_config,
                                             mock_dcp_world_size):
+        if not torch.npu.is_available():
+            self.skipTest("NPU not available, skipping NPU-dependent tests")
         mock_dcp_world_size.return_value = 1
 
         common_attn_metadata = AscendCommonAttentionMetadata(
@@ -506,6 +508,8 @@ class TestAscendMLAMetadataBuilderBuild(TestBase):
     @patch("vllm_ascend.attention.mla_v1.get_ascend_config")
     def test_build_chunked_prefix_metadata(self, mock_get_ascend_config,
                                            mock_dcp_world_size):
+        if not torch.npu.is_available():
+            self.skipTest("NPU not available, skipping NPU-dependent tests")
         mock_dcp_world_size.return_value = 1
 
         common_attn_metadata = AscendCommonAttentionMetadata(