[CI] Fix nightly CI (#3821)

### What this PR does / why we need it?
This patch fix the nightly CI runs
[failure](https://github.com/vllm-project/vllm-ascend/actions/runs/18848144365)

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

### How was this patch tested?


- vLLM version: v0.11.0rc3
- vLLM main:
https://github.com/vllm-project/vllm/commit/releases/v0.11.1

---------

Signed-off-by: wangli <wangli858794774@gmail.com>

tests/e2e/nightly/multi_node/config/multi_node_config.py

@@ -84,16 +84,17 @@ class MultiNodeConfig:
         self.envs["LOCAL_IP"] = self.cur_ip
         self.envs["NIC_NAME"] = self.nic_name
 
+        master_ip = self.cluster_ips[0]
         if self.disaggregated_prefill:
             self.envs[
                 "DISAGGREGATED_PREFILL_RANK_TABLE_PATH"] = self.disaggregated_prefill.get(
                     "ranktable_path")
             if self.cur_index < self.decode_start_index:
-                self.envs["MASTER_IP"] = self.cluster_ips[0]
+                master_ip = self.cluster_ips[0]
             else:
-                self.envs["MASTER_IP"] = self.cluster_ips[
-                    self.decode_start_index]
+                master_ip = self.cluster_ips[self.decode_start_index]
 
+        self.envs["MASTER_IP"] = master_ip
         ascend_path = "/usr/local/Ascend/ascend-toolkit/latest/python/site-packages"
         self.envs[
             "LD_LIBRARY_PATH"] = f"{ascend_path}:{self.envs.get('LD_LIBRARY_PATH', os.environ.get('LD_LIBRARY_PATH', ''))}"
@@ -288,8 +289,3 @@ class MultiNodeConfig:
         subprocess.run(cmd, env=env, check=True)
         assert os.path.exists(
             str(ranktable_path)), "failed generate ranktable.json"
-
-
-if __name__ == '__main__':
-    config = MultiNodeConfig.from_yaml()
-    print(config.perf_cmd)