[google] add missing public image projects
[google] add missing public image projects

This adds all other public image projects supported by the `gcloud` tool from
Google Cloud SDK to be automatically supported by Salt. The list of such images
are listed here: https://cloud.google.com/compute/docs/operating-systems/ and
can be found via `gcloud compute images list`.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt