Currently, the openshift-enterprise-tests image depends on the openstack repository on the x86_64 and ppc64le repositories. The package python-cinder gets installed, to allow the [openstack end-to-end tests|https://github.com/openshift/release/blob/60fed3474509bff9c5585a736554739e8ec4f017/ci-operator/step-registry/openstack/test/e2e/openstack-test-e2e-chain.yaml#L5] to [run|https://github.com/openshift/openstack-test/]. 

The python-cinder package is not made available for rhel9 on ppc64le. To move the tests image to rhel9, OCP probably should follow upstream's decision to not support ppc64le.