- [ ] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.
- [ ] I have checked the [FAQ](https://github.com/apache/dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 3.0.3-SNAPSHOT
* Operating System version: macos
* Java version: 1.8

### Steps to reproduce this issue

1.  provider export multi protocol 
```java
class ApiMigrationBothProvider {

    public static void main(String[] args) {

        ServiceConfig<IWrapperGreeter> service = new ServiceConfig<>();
        service.setInterface(IWrapperGreeter.class);
        service.setRef(new IGreeter2Impl());

        DubboBootstrap bootstrap = DubboBootstrap.getInstance();
        bootstrap.application(new ApplicationConfig("demo-migration-both-provider"))
                .registry(new RegistryConfig(TriSampleConstants.ZK_ADDRESS))
                .protocol(new ProtocolConfig(CommonConstants.TRIPLE, TriSampleConstants.SERVER_PORT))
                .protocol(new ProtocolConfig(CommonConstants.DUBBO, TriSampleConstants.DEFAULT_DUBBO_PORT))
                .service(service)
                .start()
                .await();

    }
}
```


2. run provider

## reason

![image](https://user-images.githubusercontent.com/20179425/132439980-d5916e9d-073d-425a-9171-fe81a87a53f3.png)
 
when the second protocol export, contains always true 



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

https://github.com/apache/dubbo-samples/pull/356

### Expected Result

everything is ok

### Actual Result

throw exception

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

```
java.lang.RuntimeException
	at org.apache.dubbo.registry.client.metadata.MetadataServiceNameMapping.map(MetadataServiceNameMapping.java:88)
	at org.apache.dubbo.config.ServiceConfig.lambda$exported$1(ServiceConfig.java:270)
	at java.util.ArrayList.forEach(ArrayList.java:1259)
	at org.apache.dubbo.config.ServiceConfig.exported(ServiceConfig.java:266)
	at org.apache.dubbo.config.ServiceConfig.doExport(ServiceConfig.java:371)
	at org.apache.dubbo.config.ServiceConfig.export(ServiceConfig.java:244)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.exportServices(DubboBootstrap.java:1476)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.doStart(DubboBootstrap.java:1190)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.start(DubboBootstrap.java:1166)
	at org.apache.dubbo.sample.tri.migration.ApiMigrationBothProvider.main(ApiMigrationBothProvider.java:44)
```

String serviceInterface = url.getServiceInterface();
        String registryCluster = getRegistryCluster(url);
        MetadataReport metadataReport = metadataReportInstance.getMetadataReport(registryCluster);
        return metadataReport.getServiceAppMapping(serviceInterface, url);
    }
    @Override
    public Set<String> getAndListen(URL url, MappingListener mappingListener) {
        String serviceInterface = url.getServiceInterface();
        String registryCluster = getRegistryCluster(url);
        MetadataReport metadataReport = metadataReportInstance.getMetadataReport(registryCluster);
        return metadataReport.getServiceAppMapping(serviceInterface, mappingListener, url);
    }
    @Override
    public void setApplicationModel(ApplicationModel applicationModel) {
        super.setApplicationModel(applicationModel);
        metadataReportInstance = applicationModel.getBeanFactory().getBean(MetadataReportInstance.class);
    }
    protected String getRegistryCluster(URL url) {
        String registryCluster = RegistryClusterIdentifier.getExtension(url).providerKey(url);
        if (registryCluster == null) {
            registryCluster = DEFAULT_KEY;
        }
        int i = registryCluster.indexOf(",");
        if (i > 0) {
            registryCluster = registryCluster.substring(0, i);
        }
        return registryCluster;
    }
}