tifdIndex so it's not null

Signed-off-by: Joanne Wang <jowg@amazon.com>

src/main/java/org/opensearch/securityanalytics/threatIntel/action/ThreatIntelHighLevelHandler.java

@@ -95,6 +95,7 @@ public void getThreatIntelFeedData(
                 public void onResponse(AcknowledgedResponse acknowledgedResponse) {
                     log.debug("Acknowledged threat intel feed updater job created");
                     countDownLatch.countDown();
+                    String tifdIndex = getLatestIndexByCreationDate();
                     threatIntelFeedDataService.getThreatIntelFeedData(listener, tifdIndex);
                 }
                 @Override