[fix][test] Fix flaky test OneWayReplicatorUsingGlobalZKTest.testConfigReplicationStartAt (apache#24011)

(cherry picked from commit 8b196d8)
(cherry picked from commit c05e998)

Author: poorbarcode

pulsar-broker/src/test/java/org/apache/pulsar/broker/service/OneWayReplicatorUsingGlobalZKTest.java

@@ -156,6 +156,10 @@ public void testConfigReplicationStartAt() throws Exception {
         p1.close();
 
         admin1.namespaces().setNamespaceReplicationClusters(ns1, new HashSet<>(Arrays.asList(cluster1, cluster2)));
+        Awaitility.await().untilAsserted(() -> {
+            assertTrue(admin2.topics().getList(ns1).contains(topic1));
+        });
+        admin2.topics().createSubscription(topic1, subscription1, MessageId.earliest);
         org.apache.pulsar.client.api.Consumer<String> c1 = client2.newConsumer(Schema.STRING).topic(topic1)
                 .subscriptionName(subscription1).subscribe();
         Message<String> msg2 = c1.receive(2, TimeUnit.SECONDS);