VolumeSnapshots are not getting removed when using 'velero backup delete'

Description of problem:

• When deleting backups with 'velero' tool, volumeSnapshot and volumeSnapshotContents are not getting deleted from neither OCP nor storage backend

Version-Release number of selected component (if applicable):

 - OCP 4.12.20
 - OADP 1.2
 - IBM VPC Block CSI driver 5.0.16_127

How reproducible:

 - All the time on customer's environment

Steps to Reproduce:
1. Run a backup against a namespace which contains a PVC provisioned by the CSI driver but do not have a running Pod which uses it to avoid mounting the volume on a node to simulate the failure.
2. Backup will complete with Partially failed status which is expected since the volume was not able to be snapshoted due to CSI limitation [1], volsnap and volsnapcontent objects will be created.
3. Delete backup with 'velero backup delete <backup-name>' command 

Actual results:

 - volumeSnapshot and volumeSnapshotContent objects will remain in the OCP cluster.
 - OADP won't delete these objects from the OCP cluster.

Expected results:

 - Velero / OADP should be able to delete volumeSnapshot and volumeSnapshotContent objects when createSnapshot call fails and volsnap stays with ReadyToUse=false

Additional info:

[1] https://cloud.ibm.com/docs/openshift?topic=openshift-vpc-volume-snapshot#vpc-create-snapshot