[BugFix] Fix mooncake bug in PCP scenario (#5055)

### What this PR does / why we need it?
The mooncake_connector.py file was importing the wrong arguments to the
file, which could cause errors when use PCP; this issue has been
corrected.

### Does this PR introduce _any_ user-facing change?
NO
### How was this patch tested?

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

---------

Signed-off-by: daishixun <dsxsteven@sina.com>

tests/ut/kv_connector/test_mooncake_connector.py

@@ -22,6 +22,7 @@ sys.modules["mooncake.engine"] = fake_engine
 _mock_ascend_config = MagicMock(enable_kv_nz=False)
 _mock_pp_group = MagicMock(rank_in_group=0, world_size=1)
 _mock_tp_group = MagicMock(rank_in_group=0, world_size=4)
+_mock_pcp_group = MagicMock(rank_in_group=0, world_size=1)
 patch('vllm_ascend.distributed.mooncake_connector.get_pp_group',
       return_value=_mock_pp_group).start()
 patch('vllm_ascend.distributed.mooncake_connector.get_tp_group',
@@ -32,6 +33,8 @@ patch(
 patch(
     'vllm_ascend.distributed.mooncake_connector.get_tensor_model_parallel_rank',
     return_value=0).start()
+patch('vllm_ascend.distributed.mooncake_connector.get_pcp_group',
+      return_value=_mock_pcp_group).start()
 
 from vllm_ascend.distributed.mooncake_connector import (  # noqa: E402
     KVCacheRecvingThread, KVCacheSendingThread, KVCacheTaskTracker,