It looks like /usr/bin/python *may* no longer exists in the latest cloud
builder git image. I ran the latest image and logged into it to verify
that /usr/bin/python3 does exist on 9/25, and again on 9/26 where it
re-appeared.
I think it is generally a good idea to not rely on it being there going
forward.
* Change tld-update to db-object-updater
* rename sync_tlds.sh to sync_db_objects.sh
* Change to configured command name
* Change environment to sandbox explicitly for testing on alpha
* Add remaining object steps and change cloudbuild-tld-sync to cloudbuild-sync-db-objects
* Add build_environment flag
* Change order of command and directory
* Uncomment out reserved list part