[Bug] 403 error code when requesting nacos openapi

- [x] I have searched the [issues](https://github.com/apache/dubbo-admin/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [REAMDE](https://github.com/apache/dubbo-admin/blob/develop/README.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo Admin version: develop
* Registry center detail (type and version): nacos 2.5.0
* Operating System version: macos 15.4.1
* Java version: 17.0.9

### Steps to reproduce this issue

Nacos is configured as our service registry with authentication credentials. The following error occurred during service initialization:

### Expected Result

The service started successfully with no errors.

### Actual Result

The following error occurred during service initialization:
```
2025-04-18 16:32:51.037 ERROR 24150 --- [pool-7-thread-1] o.a.d.a.registry.nacos.NacosOpenapiUtil : [DUBBO] Error requesting nacos openapi, http://127.0.0.1:8848/nacos/v1/ns/service/subscribers?serviceName=demo-service&namespaceId=public&groupName=DEFAULT_GROUP, error code is 403, dubbo version: 3.2.5, current host: x.x.x.x
```

Start by reproducing the service initialization with Nacos 2.5.0, authentication credentials, Java 17, and the develop version, then inspect the NacosOpenapiUtil path shown in the error. Done means the service starts successfully without the reported 403 error when requesting the Nacos openapi endpoint.

Written by the indexing model from the issue text.