fix mooncake connector adxl hostname usage (#2824)

### What this PR does / why we need it?
This PR is used to adapt the hostname format for Mooncake when using
adxl. When Mooncake uses adxl, it is necessary to set
```USE_ASCEND_DIRECT``` to True in the file
```/Mooncake/mooncake-common/common.cmake``` during compilation. The
mooncake_connector obtains this config by calling
```vllm_config.kv_transfer_config.get_from_extra_config```, determines
whether Mooncake is using adxl, and selects the corresponding hostname
format.

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

### How was this patch tested?
By CI.


- vLLM version: main
- vLLM main:
d21a36f5f9

---------

Signed-off-by: nwpu-zxr <zhouxuerong2@huawei.com>

vllm_ascend/distributed/mooncake_connector.py

@@ -782,10 +782,12 @@ class MooncakeConnectorWorker:
         assert len(device_ids) > self.tp_rank  # type: ignore
         self.device_id = device_ids[self.tp_rank]  # type: ignore
 
-        self._initialize(
-            hostname=self.side_channel_host + ':' + '0' + ':' + 'npu_' \
-                     + str(self.device_id),
-            device_name=None)
+        if vllm_config.kv_transfer_config.get_from_extra_config(
+                'use_ascend_direct', False):
+            hostname = self.side_channel_host
+        else:
+            hostname = f"{self.side_channel_host}:0:npu_{self.device_id}"
+        self._initialize(hostname=hostname, device_name=None)
         self.te_rpc_port = self.engine.get_rpc_port()
 
         # Background thread for sending or receiving KV caches.