nixos/libvirt: Remove non-functional service libvirt-guests

It doesn't have a start script, so it hasn't worked at all in
a long time.

nixos/modules/virtualisation/libvirtd.nix

@@ -162,34 +162,6 @@ in
           '';
       };
 
-    systemd.services."libvirt-guests" = {
-      description = "Libvirt Virtual Machines";
-
-      wantedBy = [ "multi-user.target" ];
-      wants = [ "libvirtd.service" ];
-      after = [ "libvirtd.service" ];
-
-      restartIfChanged = false;
-
-      path = with pkgs; [ gettext libvirt gawk ];
-
-      preStart = ''
-        mkdir -p /var/lock/subsys -m 755
-        ${pkgs.libvirt}/etc/rc.d/init.d/libvirt-guests start || true
-      '';
-
-      postStop = ''
-        export PATH=${pkgs.gettext}/bin:$PATH
-        export ON_SHUTDOWN=${cfg.onShutdown}
-        ${pkgs.libvirt}/etc/rc.d/init.d/libvirt-guests stop
-      '';
-
-      serviceConfig = {
-        Type = "oneshot";
-        RemainAfterExit = true;
-      };
-    };
-
     users.extraGroups.libvirtd.gid = config.ids.gids.libvirtd;
 
   };