[BUG] Update cluster retentionPeriod without change PITR backup retention"

[fengluodb]

Updating cluster retentionPeriod should also change PITR backup retention in backup schedule.

When updating cluster retentionPeriod, PITR backup retention should be adjusted accordingly in the backup schedule. This alignment is crucial to prevent scenarios where continuous backups have shorter retention periods than full backups, which could compromise the ability to restore to any point in time.

apiVersion: apps.kubeblocks.io/v1alpha1
kind: Cluster
metadata:
  creationTimestamp: "2024-10-17T02:01:12Z"
  finalizers:
  - cluster.kubeblocks.io/finalizer
  name: azoll-7558fdb4
  namespace: kubeblocks-cloud-ns
spec:
  backup:
    cronExpression: 0 18 * * *
    enabled: true
    method: xtrabackup
    pitrEnabled: true
    repoName: storage-minio
    retentionPeriod: 10d
  clusterDefinitionRef: apecloud-mysql
  clusterVersionRef: ac-mysql-8.0.30-1
  componentSpecs:
  - componentDefRef: mysql
    disableExporter: true
    enabledLogs:
    - slow
    - error
    name: mysql
    replicas: 1
    resources:
      limits:
        cpu: "1"
        memory: 1Gi
      requests:
        cpu: 100m
        memory: 102Mi
    volumeClaimTemplates:
    - name: data
      spec:
        accessModes:
        - ReadWriteOnce
        resources:
          requests:
            storage: 20Gi
        storageClassName: ape-local-hostpath-sc
  terminationPolicy: Delete

apiVersion: dataprotection.kubeblocks.io/v1alpha1
kind: BackupSchedule
metadata:
  annotations:
    apps.kubeblocks.io/backup-policy-template: apecloud-mysql-backup-policy-template
    dataprotection.kubeblocks.io/is-default-policy: "true"
    kubeblocks.io/reconcile: "435821487"
  creationTimestamp: "2024-10-17T02:01:12Z"
  finalizers:
  - cluster.kubeblocks.io/finalizer
  - dataprotection.kubeblocks.io/finalizer
  generation: 3
  namespace: kubeblocks-cloud-ns
  ownerReferences:
  - apiVersion: apps.kubeblocks.io/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: Cluster
    name: azoll-7558fdb4
    uid: 44e79f6b-8c01-4900-9516-624f723e7cf4
  resourceVersion: "435821496"
  uid: 3fdaf9a1-723f-4cd5-90f1-afab46ba0752
spec:
  backupPolicyName: azoll-7558fdb4-mysql-backup-policy
  schedules:
  - backupMethod: xtrabackup
    cronExpression: 0 18 * * *
    enabled: true
    retentionPeriod: 10d
  - backupMethod: volume-snapshot
    cronExpression: 0 18 * * *
    enabled: false
    retentionPeriod: 7d
  - backupMethod: archive-binlog
    cronExpression: '*/30 * * * *'
    enabled: true
    retentionPeriod: 8d