[Bug] MQTT cant use new user except root!!

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/iotdb/issues) and found nothing similar.

### Version

1.2.*

### Describe the bug and provide the minimal reproduce step

when create a new user in iotdb, it can login iotdb server,but cant use MQTT by this user

### What did you expect to see?

need to use other user to use MQTT

### What did you see instead?

null

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

The report names IoTDB 1.2.* and MQTT but provides no file, test, or entry point. First reproduce MQTT access with a newly created non-root user and compare it with root access; done means a non-root user can use MQTT successfully.

Written by the indexing model from the issue text.