CKAN creates a default user when it starts the development server.
ckan -c /etc/ckan/production.ini run --host 0.0.0.0 --port 5000
If the the default user is deleted and ckan is restarted again, it appears again. I don't want to have a default sysadmin user since I have my own admin user
The site_user is created on startup and its used only for internal services. If it gets removed it will be recreated on every get_site_user call