install-darwin-multi-user.sh: Remove superfluous nix.conf settings
install-darwin-multi-user.sh: Remove superfluous nix.conf settings

layus/nix,NixOS/nix,rycee/nix,layus/nix,shlevy/nix,pikajude/nix,dtzWill/nix,NixOS/nix,rycee/nix,ehmry/nix,peti/nix,pikajude/nix,zimbatm/nix,NixOS/nix,layus/nix,dezgeg/nix,dezgeg/nix,shlevy/nix,vcunat/nix,dtzWill/nix,vcunat/nix,vcunat/nix,zimbatm/nix,dtzWill/nix,dezgeg/nix,dtzWill/nix,dtzWill/nix,NixOS/nix,dezgeg/nix,ehmry/nix,pikajude/nix,zimbatm/nix,ehmry/nix,ehmry/nix,peti/nix,ehmry/nix,rycee/nix,shlevy/nix,rycee/nix,layus/nix,rycee/nix,layus/nix,vcunat/nix,zimbatm/nix,NixOS/nix,peti/nix,shlevy/nix,peti/nix,shlevy/nix,ehmry/nix,dezgeg/nix,peti/nix