nixos/terminfo: Simplify sudo-related option

nixos/modules/config/terminfo.nix

···
     };
 
     security.sudo.keepTerminfo = mkOption {
-      default = config.security.sudo.package.pname != "sudo-rs";
-      defaultText = literalMD ''
-        `true` unless using `sudo-rs`
-      '';
+      default = true;
       type = types.bool;
       description = lib.mdDoc ''
         Whether to preserve the `TERMINFO` and `TERMINFO_DIRS`