Switch to systemd-journal group

Starting with systemd-199 the group to access the systemd journal group has been changed to the upstream group name: systemd-journal; until systemd-198 the adm system group was used for this purpose.

After upgrading to systemd>=199 the systemd-journal group (with gid 24) will be created automatically. If you want to have access to the journal files your user must be added to this group:

# usermod -a -G systemd-journal <user>