Skip artifact's metadata generation if artifact_format is gzip
This is a part of https://gitlab.com/gitlab-org/gitlab-ce/issues/46809
- Gitlab-rails: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20293
- Gitlab-workhorse: here
- Gitlab-runner: gitlab-runner!923 (merged)
/cc @ayufan
Edited by Shinya Maeda