### Environment

* Dubbo version: dubbo-registry-nacos 2.7.6
* Operating System version: Win10
* Java version: JAVA 8

### Steps to reproduce this issue
1 springboot  yml配置如下： 
registry:
     address: nacos://127.0.0.1:8848
     simplified: true
     group: dubbo-local
  metadata-report:
            address: nacos://127.0.0.1:8848
            group: dubbo-local

2 登陆nacos 1.2.1 控制台发现元数据 group配置生效，但是服务管理下的group依旧是DEFAULT_GROUP。

3 跟了下dubbo-registry-nacos 2.7.6的代码 发现在调用NamingService中 没有传入配置的group参数，使用的默认组参数 
 public void doRegister(URL url) {
        String serviceName = this.getServiceName(url);
        Instance instance = this.createInstance(url);
        this.execute((namingService) -> {
            namingService.registerInstance(serviceName, instance);
        });
    }

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

### Actual Result

What actually happens?

If there is an exception, please attach the exception trace:

```
Just put your stack trace here!
```

private void subscribeEventListener(String serviceName, final URL url, final NotifyListener listener)
            throws NacosException {
        EventListener eventListener = event -> {
            if (event instanceof NamingEvent) {
                NamingEvent e = (NamingEvent) event;
                List<Instance> instances = e.getInstances();
                if(isServiceNamesWithCompatibleMode(url)){
                    /**
                     * Get all instances with corresponding serviceNames to avoid instance overwrite and but with empty instance mentioned
                     * in https://github.com/apache/dubbo/issues/5885 and https://github.com/apache/dubbo/issues/5899
                     */
                    NacosInstanceManageUtil.initOrRefreshServiceInstanceList(serviceName, instances);
                    instances = NacosInstanceManageUtil.getAllCorrespondingServiceInstanceList(serviceName);
                }
                notifySubscriber(url, listener, instances);
            }
        };
        namingService.subscribe(serviceName, eventListener);
    }
    /**
     * Notify the Healthy {@link Instance instances} to subscriber.
     *
     * @param url       {@link URL}
     * @param listener  {@link NotifyListener}
     * @param instances all {@link Instance instances}
     */
    private void notifySubscriber(URL url, NotifyListener listener, Collection<Instance> instances) {
        List<Instance> healthyInstances = new LinkedList<>(instances);
        if (healthyInstances.size() > 0) {