programs: make console/sysadmin package default on, not forced on

hosts/common/default.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ lib, pkgs, ... }:
 {
   imports = [
     ./cross.nix
@@ -19,8 +19,8 @@
   ];
 
   sane.nixcache.enable-trusted-keys = true;
-  sane.programs.sysadminUtils.enableFor.system = true;
-  sane.programs.consoleUtils.enableFor.user.colin = true;
+  sane.programs.sysadminUtils.enableFor.system = lib.mkDefault true;
+  sane.programs.consoleUtils.enableFor.user.colin = lib.mkDefault true;
 
   # some services which use private directories error if the parent (/var/lib/private) isn't 700.
   sane.fs."/var/lib/private".dir.acl.mode = "0700";