Switch Elasticsearch to 5 version

Change-Id: Ic5f0937b6288b181a6b8708a85173ad15eb4d65c
diff --git a/metadata/service/client.yml b/metadata/service/client.yml
index 203c763..72efe86 100644
--- a/metadata/service/client.yml
+++ b/metadata/service/client.yml
@@ -2,7 +2,7 @@
 - elasticsearch
 parameters:
   _param:
-    elasticsearch_version: 2
+    elasticsearch_version: 5
   elasticsearch:
     client:
       enabled: true