### 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!
```

for (String serviceName : serviceNames) {
                    List<Instance> instances = namingService.getAllInstances(serviceName);
                    NacosInstanceManageUtil.initOrRefreshServiceInstanceList(serviceName, instances);
                    allCorrespondingInstanceList.addAll(instances);
                }
                notifySubscriber(url, listener, allCorrespondingInstanceList);
                for (String serviceName : serviceNames) {
                    subscribeEventListener(serviceName, url, listener);
                }
            } else {
                List<Instance> instances = new LinkedList();
                for (String serviceName : serviceNames) {
                    instances.addAll(namingService.getAllInstances(serviceName));
                    notifySubscriber(url, listener, instances);
                    subscribeEventListener(serviceName, url, listener);
                }
            }
        });
    }
    /**
     * Since 2.7.6 the legacy service name will be added to serviceNames
     * to fix bug with https://github.com/apache/dubbo/issues/5442
     *
     * @param url
     * @return
     */
    private boolean isServiceNamesWithCompatibleMode(final URL url) {
        if (!isAdminProtocol(url) && createServiceName(url).isConcrete()) {
            return true;
        } else {