Summary

Remove parallel-netcdf dependency from base-env. Instead, add it to jedi-mpas-env and enable the variant +pnetcdf for parallelio in jedi-mpas-env (the default for this variant is ~pnetcdf).

This means that environments using template neptune-dev concretize without parallel-netcdf, but any template that includes jedi-mpas-env (e.g. unified-dev, skylab-dev) concretize with parallel-netcdf.

I added neptune-dev as an additional template to the Ubuntu GNU runner, but had to disable the xnrl variant since this package isn't publicly available. For neptune-dev, parallel-netcdf is removed, for unified-dev and skylab-dev, it is included as before.

Testing

I tested this on my laptop and I also confirmed that the CI builds behave as expected (see https://github.com/JCSDA/spack-stack/actions/runs/14740976173/job/41378625127?pr=1621)

Applications affected

None - NEPTUNE doesn't use parallel-netcdf, and the other environments in use will still have it.

Systems affected

None

Dependencies

None

Issue(s) addressed

Closes #1613

Checklist

• This PR addresses one issue/problem/enhancement, or has a very good reason for not doing so.
• These changes have been tested on the affected systems and applications.
• All dependency PRs/issues have been resolved and this PR can be merged.