[7.x] Convert module/mappers-extra to an internal cluster test (#65971)…

… (#66028)

modules/mappers-extra should be an internal cluster, not
a javaRestTest. This test will work correctly until you
you try to modify the javaRestTest test cluster. Then
it will treat the javaRestTest as an external cluster
to it's own test cluster potentially causing issues with
tests.

modules/mapper-extras/build.gradle

@@ -17,7 +17,7 @@
  * under the License.
  */
 apply plugin: 'elasticsearch.yaml-rest-test'
-apply plugin: 'elasticsearch.java-rest-test'
+apply plugin: 'elasticsearch.internal-cluster-test'
 
 esplugin {
   description 'Adds advanced field mappers'

modules/mapper-extras/src/javaRestTest/java/org/elasticsearch/index/mapper/TokenCountFieldMapperIntegrationIT.java → modules/mapper-extras/src/internalClusterTest/java/org/elasticsearch/index/mapper/TokenCountFieldMapperIntegrationIT.java

@@ -29,6 +29,7 @@
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.query.QueryBuilders;
+import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.search.aggregations.AggregationBuilders;
 import org.elasticsearch.search.aggregations.bucket.terms.Terms;
@@ -37,6 +38,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
@@ -66,6 +68,11 @@ public TokenCountFieldMapperIntegrationIT(@Name("storeCountedFields") boolean st
         this.loadCountedFields = loadCountedFields;
     }
 
+    @Override
+    protected Collection<Class<? extends Plugin>> nodePlugins() {
+        return Arrays.asList(MapperExtrasPlugin.class);
+    }
+
     /**
      * It is possible to get the token count in a search response.
      */