KAFKA-19784: Fix unit test

Author: jiafu1115

clients/src/test/java/org/apache/kafka/clients/admin/KafkaAdminClientTest.java

@@ -4758,6 +4758,7 @@ public void testDescribeOldAndNewConsumerGroups() throws Exception {
                     new MemberDescription(
                         "memberId",
                         Optional.of("instanceId"),
+                        Optional.of("rackid"),
                         "clientId",
                         "host",
                         new MemberAssignment(