Medusa purge cronjob should be created in the operator namespace

[emerkle826]

When creating the CronJob to purge Medusa backups, the initial implementation did not take into consideration that service accounts are namespaced scoped. As such, the CronJob is created in the namespace of the cluster, and not the operator. The CronJob should be created in the namesspace of the operator to function correctly in all deployments.