Use AlmaLinux for CI

For generic automation tasks using a small and easy to use container of any kind is fine, but for CI builds, developers ideally have a build and test environment that matches production as closely as possible. Since JLab uses Red Hat Enterprise Linux 9 primarily, that means ideally we'd be using Red Hat's ubi9 container. However, it's super onerous to use that container because it is encumbered with subscription entitlement management burdens. It turns out there is an alternative unencumbered distro that tracks RHEL9 binary combability: AlmaLinux.

Note: JLab pays for Enterprise Linux and for OpenShift, so it should be possible to use ubi9 as an entitled build, it just seems like more trouble than it's worth. Also note that if you don't enable entitlements the package manager is crippled and only baseOS repo packages appear to be accessible.