rustdesk-server: use DynamicUser

        Slice = "system-rustdesk.slice";

        User  = "rustdesk";

        Group = "rustdesk";

        DynamicUser = "yes";

        Environment = [];

        WorkingDirectory = "/var/lib/rustdesk";

        StateDirectory   = "rustdesk";

        StateDirectoryMode = "0750";

        LockPersonality = true;

        NoNewPrivileges = true;

        PrivateDevices = true;

        PrivateMounts = true;

        PrivateTmp = true;

        PrivateUsers = true;

        ProtectClock = true;

        ProtectControlGroups = true;

        ProtectKernelModules = true;

        ProtectKernelTunables = true;

        ProtectProc = "invisible";

        ProtectSystem = "strict";

        RemoveIPC = true;

        RestrictNamespaces = true;

        RestrictSUIDSGID = true;

      };

    };

  in lib.mkIf cfg.enable {