chore: Figure out how to matrix out builds here

[castrojo]

The base image doesn't change much stuff so it's pretty easy to have just the one Containerfile.

The ubuntu image is more opinionated and depends on COPRs and packages that might change between fedora versions. So we either template the heck out of the existing Containerfile, or we do like Containerfile.37, Containerfile.38.

I am leaning towards the 2nd solution because 37 is pretty stable now and I see us only adding new stuff in new versions and keeping the older versions more finished and stable. s We'd only have three versions that are supported at one time so we wouldn't be drowning in Containerfiles. What do people think? cc @lazypower