[TEST] declare support for groovy-scripting feature in the Java REST tests runner

Groovy was disabled by default, but we turn it on in our test infra. We can then declare support for it so we go and execute script related tests as part of the REST tests suite.

src/test/java/org/elasticsearch/test/rest/support/Features.java

@@ -34,7 +34,7 @@ import java.util.List;
  */
 public final class Features {
 
-    private static final List<String> SUPPORTED = Lists.newArrayList("gtelte", "stash_in_path");
+    private static final List<String> SUPPORTED = Lists.newArrayList("gtelte", "stash_in_path", "groovy_scripting");
 
     private Features() {