### 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!
```

*
     * @param url {@link URL}
     * @return non-null
     * @since 2.7.6
     */
    private String getLegacySubscribedServiceName(URL url) {
        StringBuilder serviceNameBuilder = new StringBuilder(DEFAULT_CATEGORY);
        appendIfPresent(serviceNameBuilder, url, INTERFACE_KEY);
        appendIfPresent(serviceNameBuilder, url, VERSION_KEY);
        appendIfPresent(serviceNameBuilder, url, GROUP_KEY);
        return serviceNameBuilder.toString();
    }
    private void appendIfPresent(StringBuilder target, URL url, String parameterName) {
        String parameterValue = url.getParameter(parameterName);
        if (!org.apache.commons.lang3.StringUtils.isBlank(parameterValue)) {
            target.append(SERVICE_NAME_SEPARATOR).append(parameterValue);
        }
    }
    private boolean isAdminProtocol(URL url) {
        return ADMIN_PROTOCOL.equals(url.getProtocol());
    }
    private void scheduleServiceNamesLookup(final URL url, final NotifyListener listener) {
        if (scheduledExecutorService == null) {
            scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
            scheduledExecutorService.scheduleAtFixedRate(() -> {
                Set<String> serviceNames = getAllServiceNames();
                filterData(serviceNames, serviceName -> {
                    boolean accepted = false;
                    for (String category : ALL_SUPPORTED_CATEGORIES) {
                        String prefix = category + SERVICE_NAME_SEPARATOR;