Build Ruby images for unit tests
What does this MR do?
Instead of using a separate repo to store images used for tests, build them as a stage while building the builder images. Essentially, build Ruby first in a stage, push that as a separate image, and build the remaining builder images on top of those.
This makes developers' lives easier as they have one less repo to update to add support for an OS.
Related issues
Edited by Balasankar 'Balu' C