Removing extra option for gitlab:assets:compile

* Don't need to specify stage as it is inherited from the job template

.gitlab-ci.yml

@@ -696,7 +696,6 @@ gitlab:setup-mysql:
 # Frontend-related jobs
 gitlab:assets:compile:
   <<: *dedicated-no-docs-and-no-qa-pull-cache-job
-  stage: test
   image: dev.gitlab.org:5005/gitlab/gitlab-build-images:ruby-2.4.4-git-2.18-chrome-69.0-node-8.x-yarn-1.2-graphicsmagick-1.3.29-docker-18.06.1
   dependencies: []
   services: