etc/nix/configuration.nix: Force disable programs.less•••The programs.less modules is enabled by default by NixOS, and injects
some nasty global environment variables ($LESSOPEN and
$LESSKEYIN_SYSTEM), which make the experience of using less(1) much
worse and slower.
So instead on doing an 'unset LESSOPEN' or something similar, I chose to
simply disable it, and stick to the less(1) from Guix Home.