Adopt code-quality for Gitlab

[andypost]

Each test stage job could report results to MR https://docs.gitlab.com/ee/user/project/merge_requests/code_quality.html#implementing-a-custom-tool

[andypost]

sniffers and linters also could use it instead of https://docs.gitlab.com/ee/ci/unit_test_reports.html#how-to-set-it-up

[andypost]

There's good progress in core https://www.drupal.org/project/drupal/issues/2974911#comment-15562077