- Make sure to pre-install the groups systemd and udev rely on. This is needed
when the tmpfiles are run at package installation time. Theoretically with
only "Requires(pre): group()", rpm is allowed to drop the group at the end of
the package installations hence let's keep "Requires: group()" dep.
Note: this is also needed when (post)file-triggers are enabled due to the
current limitation of the default libzypp transaction backend.

- file-triggers: fix lua trigger priority for sysusers (bsc#1212376)
A single digit in the priority used for sysusers got dropped somehow and
upstream commit cd621954ed643c6ee0d869132293e26056a48826 forgot to restore it
in the lua implementation.

- file-triggers: skip the call to systemd-tmpfiles in chroot too. That way we
ensure that packages that really need the tmpfiles in advance use the right
API which is %tmpfiles_create_package.
- file-triggers: to be consistent with what we already does with tmpfiles, we
skip the call to systemd-sysusers and delay system user creations until the
next reboot.

- Temporarily add
5002-Revert-core-service-when-resetting-PID-also-reset-kn.patch until it's
backported to the next stable release
See https://github.com/systemd/systemd/pull/28000

- file-triggers: make sure to skip the call to systemd-tmpfile in the
file-triggers when running on transaction systems (bsc#1212449)
systemd-tmpfiles usually modifies paths that are not supposed to change during
transactional updates (e.g. /var, /run). On transaction systems changes will
happen on the next reboot.