Add labels on resource level resource "google_gke_backup_backup_plan"

[fulyagonultas]

Describe the bug
We are calling CFF module gke-standard and gke-autopilot and use labels. We also enforced hard-mandatory sentinel policies which check resource labels are attached to each and every resource. As labels are not added on resource level, because of the resource "google_gke_backup_backup_plan" our labels sentinel check failed.

Workaround: we use default_labels in the provider google for now. but would like to have labels on resource level.