nixos/iso-image: avoid collision between GRUB2 versions (#343992)

    # here and it causes a cyclic dependency.

    boot.loader.grub.enable = false;

    environment.systemPackages =  [ grubPkgs.grub2 grubPkgs.grub2_efi ]

    environment.systemPackages =  [ grubPkgs.grub2 ]

      ++ lib.optional (config.isoImage.makeBiosBootable) pkgs.syslinux

    ;

    system.extraDependencies = [ grubPkgs.grub2_efi ];

    # In stage 1 of the boot, mount the CD as the root FS by label so

    # that we don't need to know its device.  We pass the label of the