[ML] Increase waiting time to stabilize flaky DFA integration tests (elastic#122268)

This PR increases the waiting time for the DFA native process from 60 to 90 seconds to stabilize the flaky integration tests that sometimes fail because the job has not finished training within 60 seconds.

Author: valeriy42

x-pack/plugin/ml/qa/native-multi-node-tests/src/javaRestTest/java/org/elasticsearch/xpack/ml/integration/MlNativeDataFrameAnalyticsIntegTestCase.java

@@ -124,7 +124,7 @@ protected StopDataFrameAnalyticsAction.Response forceStopAnalytics(String id) {
     }
 
     protected void waitUntilAnalyticsIsStopped(String id) throws Exception {
-        waitUntilAnalyticsIsStopped(id, TimeValue.timeValueSeconds(60));
+        waitUntilAnalyticsIsStopped(id, TimeValue.timeValueSeconds(90));
     }
 
     protected void waitUntilAnalyticsIsStopped(String id, TimeValue waitTime) throws Exception {