fix:EtcdInstanceRegisterRepositoryTest run error (#6127)

Author: Wweiei

shenyu-registry/shenyu-registry-etcd/src/test/java/org/apache/shenyu/registry/etcd/EtcdInstanceRegisterRepositoryTest.java

@@ -152,6 +152,7 @@ public void testSelectInstancesAndWatcher() {
         })) {
             final EtcdInstanceRegisterRepository repository = new EtcdInstanceRegisterRepository();
             RegisterConfig config = new RegisterConfig();
+            config.setServerLists("http://localhost:2379");
             repository.init(config);
             repository.persistInstance(data);
             repository.selectInstances(InstancePathConstants.buildInstanceParentPath());