[TEST] Ensure the license is enabled when starting watcher

This change adds a check to make sure that the license is enabled when starting watcher in the tests.
This avoids a race-condition where a test might run before the license manager had a chance to start.

Original commit: elastic/x-pack-elasticsearch@0b9d0da5d4

src/test/java/org/elasticsearch/watcher/test/AbstractWatcherIntegrationTests.java

@@ -188,6 +188,7 @@ public abstract class AbstractWatcherIntegrationTests extends ElasticsearchInteg
 
     private void startWatcherIfNodesExist() throws Exception {
         if (internalTestCluster().size() > 0) {
+            ensureLicenseEnabled();
             WatcherStatsResponse response = watcherClient().prepareWatcherStats().get();
             if (response.getWatcherState() == WatcherState.STOPPED) {
                 logger.info("[{}#{}]: starting watcher", getTestClass().getSimpleName(), getTestName());