Don't enable nix-bash-completions when using Nix 2.4

2.4 has its own completion script which collides with
nix-bash-completions.

nixos/modules/config/system-path.nix

@@ -8,8 +8,7 @@ with lib;
 let
 
   requiredPackages = map (pkg: setPrio ((pkg.meta.priority or 5) + 3) pkg)
-    [ config.nix.package
-      pkgs.acl
+    [ pkgs.acl
       pkgs.attr
       pkgs.bashInteractive # bash with ncurses support
       pkgs.bzip2
@@ -33,7 +32,6 @@ let
       pkgs.nano
       pkgs.ncurses
       pkgs.netcat
-      pkgs.nix-info
       config.programs.ssh.package
       pkgs.perl
       pkgs.procps