In disconnected clusters the release image is mirrored. Unfortunately, "oc adm release info" command does not take /etc/containers/registries.conf mirrors into account, hence in disconnected clusters we cannot get the release image specs unless we apply the mirror manually.

When the "oc adm release info" command spec fails:
1. parse the output to get the release image name
2. search in all imagecontentsourcepolicies and all imagedigestimirrorsets if there is any mirror for the release image (it should)
3. use the mirror manually to get the image specs

The change needs to be implemented here in the MCO repo:
https://github.com/openshift/machine-config-operator/pull/5466/files/90ff44274034c0c57d5d81c9205e5ad142794d41#diff-8495c9da76dd094b95a81b521d5f6e1b6a26f4df865e4c315c7f15688f19eaaaR559

And here in the private tests repo (nevertheless, this repository should be deprecated soon):
https://github.com/openshift/openshift-tests-private/blob/master/test/extended/mco/mco_pinnedimages.go#L560