Drop conda metapackages

I am considering dropping the conda metapackages and supporting infrastructure.

The metapackages (as I see them) exist to reduce the workload of the system admin in managing a system when users request new packages, including onboarding new hardware. With Conda this is taken care of centrally by the IGWN Conda Distribution, so we have never ever used any of the conda metapackages.

It would release a small amount of workload to just stop producing conda metapackages.

/cc @adam-mercer