Merge branch 'alipniagov/fix-envfile-refs' into 'master'

Use `master` instead of `latest` in .env

See merge request gitlab-org/build/CNG!527

.env

 # Images
 GITLAB_OMNIBUS_IMAGE=gitlab/gitlab-ee:nightly
-GITLAB_RAILS_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-rails-ee:latest
-GITLAB_WEBSERVICE_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-webservice-ee:latest
-GITLAB_WORKHORSE_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-workhorse-ee:latest
-GITLAB_SIDEKIQ_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-sidekiq-ee:latest
-GITLAB_SHELL_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-shell:latest
-GITLAB_GITALY_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitaly:latest
+GITLAB_RAILS_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-rails-ee:master
+GITLAB_WEBSERVICE_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-webservice-ee:master
+GITLAB_WORKHORSE_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-workhorse-ee:master
+GITLAB_SIDEKIQ_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-sidekiq-ee:master
+GITLAB_SHELL_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitlab-shell:master
+GITLAB_GITALY_IMAGE=registry.gitlab.com/gitlab-org/build/cng/gitaly:master
 
 # Networking
 WEBSERVICE_HOST_PORT=8080