Description of problem: Label cluster.open-cluster-management.io/backup-cluster stamped 'unknown' for velero backups


Version-Release number of selected component (if applicable):
- ACM 2.5.0-DOWNSTREAM-2022-02-21-19-58-55
- MCE 2.0.0-DOWNANDBACK-2022-02-22-17-26-30

How reproducible:


Steps to Reproduce:
1. Install ACM + RH OADP v1.0.0
2. Create DPA 
3. Create backup schedule

Actual results:
Velero backups have the label 'cluster.open-cluster-management.io/backup-cluster' as unknown 


Expected results:
the label 'cluster.open-cluster-management.io/backup-cluster' should populate the current ocp clusterID

Additional info:

oc get bsch -n openshift-adp
NAME           PHASE     MESSAGE
schedule-acm   Enabled   Velero schedules are enabled


oc get backups.velero -n openshift-adp
NAME                                              AGE
acm-credentials-cluster-schedule-20220224223713   14m
acm-credentials-cluster-schedule-20220224224041   11m
acm-credentials-hive-schedule-20220224223713      14m
acm-credentials-hive-schedule-20220224224041      11m
acm-credentials-schedule-20220224223713           14m
acm-credentials-schedule-20220224224041           11m
acm-managed-clusters-schedule-20220224223713      14m
acm-managed-clusters-schedule-20220224224041      11m
acm-resources-generic-schedule-20220224223714     14m
acm-resources-generic-schedule-20220224224041     11m
acm-resources-schedule-20220224223714             14m
acm-resources-schedule-20220224224041             11m


oc get backups.velero -n openshift-adp acm-credentials-cluster-schedule-20220224223713 -oyaml
apiVersion: velero.io/v1
kind: Backup
metadata:
  annotations:
    velero.io/source-cluster-k8s-gitversion: v1.23.3+2e8bad7
    velero.io/source-cluster-k8s-major-version: "1"
    velero.io/source-cluster-k8s-minor-version: "23"
  creationTimestamp: "2022-02-24T22:37:13Z"
  generation: 5
  labels:
    cluster.open-cluster-management.io/backup-cluster: unknown
    cluster.open-cluster-management.io/backup-schedule-name: schedule-acm
    cluster.open-cluster-management.io/backup-schedule-type: credentialsCluster
    velero.io/schedule-name: acm-credentials-cluster-schedule
    velero.io/storage-location: velero-1
  name: acm-credentials-cluster-schedule-20220224223713
  namespace: openshift-adp
  resourceVersion: "74241719"
  uid: 58d97ca2-d6b8-49e0-b317-5e9da1190d4e
spec:
  defaultVolumesToRestic: false
  hooks: {}
  includeClusterResources: false
  includedResources:
  - secret
  - configmap
  labelSelector:
    matchExpressions:
    - key: cluster.open-cluster-management.io/backup
      operator: Exists
  metadata: {}
  storageLocation: velero-1
  ttl: 240h0m0s
status:
  completionTimestamp: "2022-02-24T22:38:14Z"
  expiration: "2022-03-06T22:37:44Z"
  formatVersion: 1.1.0
  phase: Completed
  progress:
    itemsBackedUp: 4
    totalItems: 4
  startTimestamp: "2022-02-24T22:37:44Z"
  version: 1