[Feature] DataBackup does not inject NodeAffinity into status after successful backup, unlike other data operations

[adityaupasani2]

What's wrong

DataBackup.OnceHandler.GetOperationStatus() in pkg/controllers/v1alpha1/databackup/status_handler.go has an unresolved TODO:

// TODO: inject nodeaffinity like other data operations when using job instead of pod

DataLoad, DataMigrate, and DataProcess all call dataflow.GenerateNodeAffinity(job) after a successful operation to populate status.nodeAffinity. This allows downstream runAfter operations to be scheduled on the same node where the data was cached, improving cache hit rates.

DataBackup uses a Pod instead of a Job, so dataflow.GenerateNodeAffinity(*batchv1.Job) cannot be called directly. As a result, DataBackup.Status.NodeAffinity is never set, breaking the dataflow affinity chain for any operation that depends on a DataBackup via runAfter.

Proposed fix

1. Add GenerateNodeAffinityFromPod(pod *corev1.Pod) to pkg/dataflow/helper.go, applying the same annotation-based logic as the existing GenerateNodeAffinity(job *batchv1.Job)
2. Call it in DataBackup.OnceHandler.GetOperationStatus() after the pod succeeds, same as other handlers do for jobs

I'd like to work on this.