Undercloud install fails with Unauthorized to get containers

Issue

• After adding my credentials to the container-image-prepare.yaml file, my undercloud install still fails with an Unauthorized for url:

tripleo_common.image.exception.ImageUploaderException: Unable to authenticate. This may indicate missing registry credentials or the provided container or namespace does not exist. 401 Client Error: Unauthorized for url: https://registry.redhat.io/auth/realms/rhcc/protocol/redhat-docker-v2/auth?service=docker-registry&scope=repository%3Arhosp-rhel8%2Fopenstack-aodh-api%3Apull