I've got no idea why it was trying to override the phase list and in
such a way. Still, it's slightly discomforting that the expansion
semantics was changed in bash.
This removes our hardcoded presets which weren't updated for quite some time.
Infinality now has new hardcoded presets in freetype, which can be overriden if
desired with environment variables (as before). Accordingly, updated NixOS
module to set the hardcoded preset.
Additionally used a more "right" type for substitutions.
