test: disable marvel for watcher with groovy tests

This commit disables marvel when running the watcher with groovy tests. Marvel creates
indices and expect the cluster to be green, which won't happen with the marvel indices
existing and expecting a replica.

See elastic/elasticsearch#1087

Original commit: elastic/x-pack-elasticsearch@8d163a53b7

elasticsearch/qa/smoke-test-watcher-with-groovy/build.gradle

@@ -10,5 +10,6 @@ integTest {
     plugin 'x-pack', project(':x-plugins:elasticsearch:x-pack')
     systemProperty 'es.script.inline', 'on'
     systemProperty 'es.shield.enabled', 'false'
+    systemProperty 'es.marvel.enabled', 'false'
   }
 }