Additional CI tests to ensure we don't break openshift

[lsm5]

OpenShift 4.16 and 4.17 were broken by https://github.com/containers/container-selinux/pull/329 so that had to be reverted in https://github.com/containers/container-selinux/pull/346 (new maint branch).

We should enable CI testing on openshift environments to ensure we don't break them. If openshift envs are difficult for CI, we should look at running minimal reproducers on rhel envs at the very least.