fix(systemd-journald): add systemd-sysusers dependency

[aafeijoo-suse]

The systemd-journald module installs its own system group, so add the missing the dependency.

https://github.com/dracutdevs/dracut/blob/a804945f27a0ccc2f69ae694599b1afec2afe8b1/modules.d/01systemd-journald/module-setup.sh#L48

Checklist

• [ ] I have tested it locally
• [ ] I have reviewed and updated any documentation if relevant
• [ ] I am providing new code and test(s) for it