CI: Remove the default alpine & ubuntu versions so that the ones in Dockerfile (#115544)
* Remove the default alpine & ubuntu versions so that the ones in Dockerfile are used
* set default to just 'alpine' or 'ubuntu'
* use defaults instead
(cherry picked from commit 39fa6559ee)
Co-authored-by: Kevin Minehart <5140827+kminehart@users.noreply.github.com>