ElasticContainer: Use 7.0.0-alpha2

Change-Id: Ied9d1de55fff994fe1ed0f4bc1a33e4b58dd4af8
diff --git a/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java b/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java
index 08e4678..b68e866 100644
--- a/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java
+++ b/gerrit-elasticsearch/src/test/java/com/google/gerrit/elasticsearch/ElasticContainer.java
@@ -47,7 +47,7 @@
       case V6_5:
         return "docker.elastic.co/elasticsearch/elasticsearch-oss:6.5.4";
       case V7_0:
-        return "docker.elastic.co/elasticsearch/elasticsearch-oss:7.0.0-alpha1";
+        return "docker.elastic.co/elasticsearch/elasticsearch-oss:7.0.0-alpha2";
     }
     throw new IllegalStateException("No tests for version: " + version.name());
   }