Merge branch 'patch-71' into 'master'

Remove duplicated line from Maven CI template

See merge request gitlab-org/gitlab-ce!31440

lib/gitlab/ci/templates/Maven.gitlab-ci.yml

-# This file is a template, and might need editing before it works on your project.
-
 # Build JAVA applications using Apache Maven (http://maven.apache.org)
 # For docker image tags see https://hub.docker.com/_/maven/
 #