nixos/moonraker: set default machine.provider to none if system control is disabled (#399976)

        platform = "linux";

        enable_estimator_updates = false;

      };

      # suppress PolicyKit warnings if system control is disabled

      machine.provider = lib.mkIf (!cfg.allowSystemControl) (lib.mkDefault "none");

    };

    security.polkit.extraConfig = lib.optionalString cfg.allowSystemControl ''