### 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!
```

NacosServiceName serviceName = createServiceName(url);
        final Set<String> serviceNames;
        if (serviceName.isConcrete()) { 
            serviceNames = new LinkedHashSet<>();
            serviceNames.add(serviceName.toString());
            
            String legacySubscribedServiceName = getLegacySubscribedServiceName(url);
            if (!serviceName.toString().equals(legacySubscribedServiceName)) {
                
                serviceNames.add(legacySubscribedServiceName);
            }
        } else {
            serviceNames = filterServiceNames(serviceName);
        }
        return serviceNames;
    }
    private Set<String> filterServiceNames(NacosServiceName serviceName) {
        Set<String> serviceNames = new LinkedHashSet<>();
        execute(namingService -> {
            serviceNames.addAll(namingService.getServicesOfServer(1, Integer.MAX_VALUE).getData()
                    .stream()
                    .map(NacosServiceName::new)
                    .filter(serviceName::isCompatible)
                    .map(NacosServiceName::toString)
                    .collect(Collectors.toList()));
        });
        return serviceNames;
    }
    /**
     * Get the legacy subscribed service name for compatible with Dubbo 2.7.3 and below