CNG: gitlab-pages contains excess

Summary

GitLab Pages images contains excess content, due to inheritance and prior reliance on gitlab-ruby.

Details

GitLab Pages has no need for Ruby during the runtime, as such, should not base based on, or rely upon gitlab-ruby image.

• Current image size: registry.gitlab.com/gitlab-org/build/cng/gitlab-pages:v1.44.0 310 MB
• Compiled gitlab-pages binary 20 MB

Related to #2697 (closed).

See gitlab-org/build/CNG!806 (comment 715013611) for details excess breakdown.

Status

Significant reduction requires #2958 (closed)

Size of images (compressed ~50%, via skopeo) as to April 20, 2022

image	size
debian	110663976
ubi	160646556