It seems these images use systemd (a nice departure from the init.d scripts used in the previous container_vms images [1]).
[1] - https://cloud.google.com/compute/docs/containers/container_v...
[1] - https://cloud.google.com/compute/docs/containers/container_v...
The previous debian based container-vm image only ran upstart.
Debian sysvinit scripts are well understood, are used in production in Fortune 500 companies, and execute much quicker on boot.
Systemd is a mistake, and no one should be backing that project.