QuickLab cluster should not leave behind unused EBS volumes

Currently, QuickLab cluster users need to remove pvc-related EBS volumes manually in AWS (look for detached volumes with names like _quicklab-gnap-cluster-dynamic-pvc-d3ab7504-7b74-4ade-962f-8f411421aaa2_), even after toggling off the cluster (`var.create_cluster = false`) and after a `terraform destroy`.