Run reindex on Ubuntu 16

Align Ubuntu Docker image with CentOS7 and create indexes
on the plain vanilla image

Change-Id: I97025e043bb2bfa2f94a495988aa3ef5cc6d9ef6

ubuntu/16/Dockerfile

diff --git a/ubuntu/16/Dockerfile b/ubuntu/16/Dockerfile
index baa1c05..87b8cd2 100644
--- a/ubuntu/16/Dockerfile
+++ b/ubuntu/16/Dockerfile
@@ -17,6 +17,7 @@
 
 USER gerrit
 RUN java -jar /var/gerrit/bin/gerrit.war init --batch --install-all-plugins -d /var/gerrit
+RUN java -jar /var/gerrit/bin/gerrit.war reindex -d /var/gerrit
 
 # Allow incoming traffic
 EXPOSE 29418 8080