The system-wide location for the containers storage.conf is
/usr/share/containers. The existence of a file in /etc/containers
completely overrides this (see containers-storage.conf(5)).
If no file is found at /etc/containers/storage.conf then fall back to
reading the config from /usr/share/containers/storage.conf.
If neither file exists, this is an error since the default config should
be packaged with any tool that requires it (skopeo, podman, etc).