Merge branch 'dd-correct-invalid-label-directive' into 'master'

Fix invalid LABEL directive

See merge request gitlab-org/gitlab!27257

qa/Dockerfile

 FROM ruby:2.6-stretch
-LABEL maintainer "Grzegorz Bizon <grzegorz@gitlab.com>"
+LABEL maintainer="GitLab Quality Department <quality@gitlab.com>"
 ENV DEBIAN_FRONTEND noninteractive
 
 ##