Watcher: Give test a little more time

Changes watcher's integration tests to wait 30 seconds when starting
watcher rather than 10 seconds because this build failed when starting
took 12 seconds:
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+6.3+periodic/222/console

Author: nik9000

x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/test/AbstractWatcherIntegrationTestCase.java

@@ -73,6 +73,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
@@ -477,8 +478,7 @@ protected void startWatcher() throws Exception {
             }
 
             throw new AssertionError("unexpected state, retrying with next run");
-        });
-
+        }, 30, TimeUnit.SECONDS);
     }
 
     protected void ensureLicenseEnabled() throws Exception {