Comment # 1 on bug 1020019 from Marcus Schaefer

The people who designed the JeOS image intentionally added that systemd service
script which asks the user for this information. This is not considered a bug
in kiwi

In order to get rid of this systemd firstboot service just remove the service
file from the overlay files (root.tar.gz) of the image description in question

I'll hand this one over to Anja