Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Upgrade elasticsearch-rest-client to 7.3.1
  Add .gitreview file

Update the newly added .gitreview file to point to stable-2.16.

Change-Id: I9ca52ec3d90dea1b44321be4eb648448abafff1e

javatests/com/google/gerrit/elasticsearch/ElasticContainer.java

@@ -59,7 +59,7 @@ public class ElasticContainer extends ElasticsearchContainer {
       case V7_2:
         return "blacktop/elasticsearch:7.2.1";
       case V7_3:
-        return "blacktop/elasticsearch:7.3.0";
+        return "blacktop/elasticsearch:7.3.1";
     }
     throw new IllegalStateException("No tests for version: " + version.name());
   }