[TEST] Only create indices if nodes exist

Some tests manually start nodes, hence in the before test phase there are no nodes around thus indices should not be created.
Relates to elastic/elasticsearch#3770

Closes elastic/elasticsearch#3812

Original commit: elastic/x-pack-elasticsearch@a21ad39903

elasticsearch/src/test/java/org/elasticsearch/xpack/watcher/test/AbstractWatcherIntegrationTestCase.java

@@ -323,6 +323,7 @@ public abstract class AbstractWatcherIntegrationTestCase extends ESIntegTestCase
      *
      */
     private void configureAliasesForWatcherIndices() throws Exception {
+        if (internalCluster().size() > 0) {
             // alias for .watches, setting the index template to the same as well
             if (rarely()) {
                 String newIndex = ".watches-alias-index";
@@ -359,6 +360,7 @@ public abstract class AbstractWatcherIntegrationTestCase extends ESIntegTestCase
                 }
             }
         }
+    }
 
     protected TimeWarp timeWarp() {
         assert timeWarped() : "cannot access TimeWarp when test context is not time warped";