Can `builtin-spack-packages`/`access-spack-packages` be informed solely by `spack-config`?

[CodeGat]

Background

There are cases where:

• We update the builtin-spack-packages ref in build-cds config/settings.json for Release and Prerelease, and
• We update the access-spack-packages ref in a MDRs config/versions.json for Release,

which is then updated in the spack instance. However, this leads to the repos.yaml coming out of sync with the spack-config (becoming modified by the spack-config repo), which is then blown away when spack-config is updated.

Implementation Details

Change config scope for builtin-spack-packages updates

Have updates to builtin-spack-packages go to a higher configuration scope, so they are not considered modified in the spack-config repository, but still take effect.

However, this will mean that spack-configs repos.yaml versions will be able to be overridden.

Have only spack-config inform builtin-spack-packages

Alternatively, don't have the builtin-spack-packages key in config/settings.json at all - just as it was beforehand. In this case, spack-config (rather than spack) will denote the version of builtin-spack-packages. More testing will need to be done regarding how to update the versions of the packages when spack-config is updated.

However, this will remain an issue for Releases for access-spack-packages - spack-config will be modified when an MDRs access-spack-packages is updated in config/versions.json.