Revert "nixos/polkit: guard static gid for polkituser behind state version"

This reverts commit 2265160fc0 and
e56db577a1.

Ideally, we shouldn't cause friction for users that bump `stateVersion`,
and I'd consider having to switch and/or manually hardcode a UID/GID
to supress the warning friction. I think it'd be more beneficial to, in
this rare case of an ID being missed, just let it be until more
discussion happens surrounding this overall issue.

See https://github.com/NixOS/nixpkgs/pull/217785 for more context.

nixos/modules/misc/ids.nix

@@ -392,7 +392,7 @@ in
       tape = 25;
       video = 26;
       dialout = 27;
-      polkituser = 28;
+      #polkituser = 28; # currently unused, polkitd doesn't need a group
       utmp = 29;
       # ddclient = 30; # converted to DynamicUser = true
       davfs2 = 31;

nixos/modules/security/polkit.nix

@@ -113,9 +113,7 @@ in
       group = "polkituser";
     };
 
-    users.groups.polkituser = {
-      gid = mkIf (lib.versionAtLeast config.system.stateVersion "23.05") config.ids.gids.polkituser;
-    };
+    users.groups.polkituser = {};
   };
 
 }