Increase timeout in AutoFollowIT (#60004)

It can take more than 10 seconds to auto-follow and create a follow-task
on a slow CI. This commit increases timeout in AutoFollowIT by replacing
assertBusy with assertLongBusy.

Closes #59952

x-pack/plugin/ccr/src/internalClusterTest/java/org/elasticsearch/xpack/ccr/AutoFollowIT.java

@@ -79,7 +79,7 @@ public void testAutoFollow() throws Exception {
         createLeaderIndex("metrics-201901", leaderIndexSettings);
 
         createLeaderIndex("logs-201901", leaderIndexSettings);
-        assertBusy(() -> {
+        assertLongBusy(() -> {
             IndicesExistsRequest request = new IndicesExistsRequest("copy-logs-201901");
             assertTrue(followerClient().admin().indices().exists(request).actionGet().isExists());
         });
@@ -262,7 +262,7 @@ public void testAutoFollowParameterAreDelegated() throws Exception {
         assertTrue(followerClient().execute(PutAutoFollowPatternAction.INSTANCE, request).actionGet().isAcknowledged());
 
         createLeaderIndex("logs-201901", leaderIndexSettings);
-        assertBusy(() -> {
+        assertLongBusy(() -> {
             FollowInfoAction.Request followInfoRequest = new FollowInfoAction.Request();
             followInfoRequest.setFollowerIndices("copy-logs-201901");
             FollowInfoAction.Response followInfoResponse;