phpfpm service: remove NoNewPrivileges systemd option

This interferes with sendmail because suid won't work. Fixes #26611.

nixos/modules/services/web-servers/phpfpm/default.nix

···
           PrivateDevices = true;
           ProtectSystem = "full";
           ProtectHome = true;
-          NoNewPrivileges = true;
           RestrictAddressFamilies = "AF_UNIX AF_INET AF_INET6";
           Type = "notify";
           ExecStart = "${cfg.phpPackage}/bin/php-fpm -y ${cfgFile} -c ${phpIni}";