MedusaBackupJob are never cleaned up

[c3-clement]

What happened?

MedusaBackupJob CRs are not deleted by k8ssandra-operator, even if purging is enabled.
They are only deleted when the corresponding CassandraDatacenter is deleted.

When they are created by a long-running MedusaBackupSchedule, the number of MedusaBackupJob CRs will grow with time.

Did you expect to see something different?

I expect the MedusaBackupJob to be automatically deleted when purging is enabled.

Since the sync MedusaTask is deleting MedusaBackup when the corresponding backup is not present in the remote bucket (which typically happens after a purge), I believe that the corresponding MedusaBackupJob should be as well deleted.

How to reproduce it (as minimally and precisely as possible):

1. Create a K8ssandraCluster with Medusa backup enabled
2. Create a MedusaBackupSchedule

Environment

• K8ssandra Operator version:
  1.14 - 1.16

• Kubernetes version information:

v1.29.3

• Kubernetes cluster kind:

AKS, EKS, GKE