### 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!
```

/**
     * A filter for Nacos data
     *
     * @since 2.6.5
     */
    private interface NacosDataFilter<T> {
        /**
         * Tests whether or not the specified data should be accepted.
         *
         * @param data The data to be tested
         * @return <code>true</code> if and only if <code>data</code>
         * should be accepted
         */
        boolean accept(T data);
    }
    /**
     * {@link NamingService} Callback
     *
     * @since 2.6.5
     */
    interface NamingServiceCallback {
        /**
         * Callback
         *
         * @param namingService {@link NamingService}
         * @throws NacosException
         */
        void callback(NamingService namingService) throws NacosException;
    }
}