Binary caching: remove symlinks, copy files instead (#9747)
Binary caching: remove symlinks, copy files instead (#9747)

* omit symlinks and create file copies when making a binary cache of a package

* unrelated flake edits involving regexes that recent flake is now angry about

LLNL/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack