Build Openshift rootless UBI images
For #27126 (closed) we need to build images that cannot be run as root.
OpenShift runs the container with a different user id each time. We need to:
- Specify a default user that isn't 0(root) - most commonly 1001
- Allow the root group to read/write to each directory in which our image might read/write. This is safe because each random user is part of the root group but the root group doesn't have any special privileges
Resources: