Clean up CronJob compatibility code

The Compliance Operator uses CronJobs to implement scan schedules.

The CronJob kubernetes API graduated from beta to stable, with the beta version no longer being supported in upstream Kubernetes, or OpenShift distributions.

This means we can clean up compatibility code needed to ensure the Compliance Operator worked on versions of OpenShift that had either the beta, or stable, CronJob APIs.

The compatibility code was implemented in https://github.com/ComplianceAsCode/compliance-operator/commit/e16c78f711c59ba3259128befe1afb46a3161a6d and can be safely removed now that OpenShift no longer supports a version of kubernetes that ships a beta CronJob API.