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

## Describe the proposal
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@wxbty PTAL
import org.apache.dubbo.config.ServiceConfig;
import org.apache.dubbo.config.bootstrap.builders.InternalServiceConfigBuilder;
import org.apache.dubbo.metrics.service.MetricsService;
import org.apache.dubbo.metrics.service.MetricsServiceExporter;
import org.apache.dubbo.rpc.model.ApplicationModel;
import org.apache.dubbo.rpc.model.ScopeModelAware;
import java.util.Optional;
import java.util.concurrent.ExecutorService;
import static org.apache.dubbo.common.constants.LoggerCodeConstants.COMMON_METRICS_COLLECTOR_EXCEPTION;
import static org.apache.dubbo.common.constants.MetricsConstants.PROTOCOL_PROMETHEUS;
/**
 * Export metrics service
 */
public class DefaultMetricsServiceExporter implements MetricsServiceExporter, ScopeModelAware {
    private final ErrorTypeAwareLogger logger = LoggerFactory.getErrorTypeAwareLogger(getClass());
    private          ApplicationModel              applicationModel;
    private          MetricsService                metricsService;
    private volatile ServiceConfig<MetricsService> serviceConfig;
    @Override
    public void init() {
        initialize();
    }
    private void initialize() {
        MetricsConfig metricsConfig = applicationModel.getApplicationConfigManager().getMetrics().orElse(null);
        
        if (metricsConfig != null &&  metricsService == null) {
            if (PROTOCOL_PROMETHEUS.equals(metricsConfig.getProtocol()) ) {
                this.metricsService  = applicationModel.getExtensionLoader(MetricsService.class).getDefaultExtension();
            } else {
                logger.warn(COMMON_METRICS_COLLECTOR_EXCEPTION, "", "", "Protocol " + metricsConfig.getProtocol() + " not support for new metrics mechanism. " +