CNG: Factor out Debian build dependencies into a builder image and use it for multi-stage build

Problem

Most Debian-based images install their build dependencies which are shared across multiple images. By extracting build dependencies into one image and using it for multi-stage build we can speed up the build process.

Proposal

We are already doing this for gitlab-ubi-builder. The same pattern can be rolled out for Debian-based images. In this case should rename gitlab-ubi-builder to a more generic name and provide variants for different build environments.