daemon: Workaround the systemd UnitNew/GetAll loop in a different way

The old workaround doesn't seem to work anymore.

Fixes #813
Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Patch things up when cockpitd fails to parse a systemd unit file

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Don't get in a tight loop when embedded journals are empty

Closes #827
Reviewed-by: Stef Walter <stefw@redhat.com>