cleanup unused buildkitd PVCs
Issue- When the statefulset is scaled down, the PVCs associated with the scaled-down pods are not automatically deleted by Kubernetes. Task - As the part of the task we have to create a program that delete unbound buildkitd PersistentVolumeClaims that have lingered past a certain amount of time since their last use (suggested default: 4 hours) in the K8 cluster.
Bug: T351478