rocketmq proxy里面findOneBroker为什么传clusterName

### Before Creating the Bug Report

- [x] I found a bug, not just asking a question, which should be created in [GitHub Discussions](https://github.com/apache/rocketmq/discussions).

- [x] I have searched the [GitHub Issues](https://github.com/apache/rocketmq/issues) and [GitHub Discussions](https://github.com/apache/rocketmq/discussions) of this repository and believe that this is not a duplicate.

- [x] I have confirmed that this bug belongs to the current repository, not other repositories of RocketMQ.

### Runtime platform environment

ubantu 20.04 Runtime platform environment: DOCKER

### RocketMQ version

5.3.1

### JDK Version

1.8

### Describe the Bug

@Override
protected SubscriptionGroupConfig getDirectly(String consumerGroup) throws Exception {
ProxyConfig config = ConfigurationManager.getProxyConfig();
String clusterName = config.getRocketMQClusterName();
Optional brokerDataOptional = findOneBroker(clusterName);
if (brokerDataOptional.isPresent()) {
String brokerAddress = brokerDataOptional.get().selectBrokerAddr();
return mqClientAPIFactory.getClient().getSubscriptionGroupConfig(brokerAddress, consumerGroup, DEFAULT_TIMEOUT);
}
return EMPTY_SUBSCRIPTION_GROUP_CONFIG;
}

### Steps to Reproduce

启动后proxy会报no topic route from namesrv

### What Did You Expect to See?

解决这个bug，发布新版本

### What Did You See Instead?

很紧急

### Additional Context

_No response_

Start by tracing the proxy's getDirectly method, especially ProxyConfig.getRocketMQClusterName(), findOneBroker(clusterName), and the subsequent getSubscriptionGroupConfig call. Reproduce the issue with RocketMQ 5.3.1 on the stated Docker environment and verify the proxy no longer reports "no topic route from namesrv".

Written by the indexing model from the issue text.