Recreate symlinks from spack-config to $spack/etc/spack after force checkout

[CodeGat]

See failed run: https://github.com/ACCESS-NRI/ACCESS-OM2/actions/runs/8447128060/job/23136977611#step:6:125
We hadn't deployed in a while, so ACCESS-NRI/spack-config@3317dd2 went under the radar. When we deployed, there were a bunch of broken symlinks, so we couldn't find the spack-packages install, and then couldn't find the access-om2 package.

We should make deployment update the symlinks after we have done a git checkout --force of spack-config.
Essentially:

rm <all the broken symlinks>
ln -s -r -v spack-config/v0.20/gadi/* spack/etc/spack/

[CodeGat]

Although this might not be an issue if ACCESS-NRI/spack-config#30 is merged