Fix NPE when using tri as metadata service protocol (#10639)

Author: AlbumenJ

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/metadata/MetadataUtils.java

@@ -137,7 +137,7 @@ public static ProxyHolder referProxy(ServiceInstance instance) {
 
         Protocol protocol = applicationModel.getExtensionLoader(Protocol.class).getAdaptiveExtension();
 
-        url.setServiceModel(consumerModel);
+        url = url.setServiceModel(consumerModel);
 
         Invoker<MetadataService> invoker = protocol.refer(MetadataService.class, url);