We need to utilize the ContainerImagePrepare parameter not only to select which images we point to in overcloud, but also to actually execute the image upload to local registry, similarly like `overcloud deploy` does.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHEA-2019:0045