Make a frozen spack version and an auto-updating version

Have a frozen spack version and an auto-updating version, our build-tracker job should pull from the frozen, and then we create a pipeline that pulls from the auto-updating version. This will take three tasks:

• Create the versions in the upstream spack repos, and make build-tracker pull from the frozen
• Make a ci variable that chooses which version you want to use spack add on
• Add a pipeline that runs on the latest version, probably weekly