GCE/AWS: Spread PetSet volume creation across zones

Long term we plan on integrating this into the scheduler, but in the
short term we use the volume name to place it onto a zone.

We hash the volume name so we don't bias to the first few zones.

If the volume name "looks like" a PetSet volume name (ending with
-<number>) then we use the number as an offset.  In that case we hash
the base name.

Fixes #27256

pkg/volume/plugins.go

@@ -49,6 +49,8 @@ type VolumeOptions struct {
 	// PV.Name of the appropriate PersistentVolume. Used to generate cloud
 	// volume name.
 	PVName string
+	// PVC.Name of the PersistentVolumeClaim, if we are auto-provisioning.
+	PVCName string
 	// Unique name of Kubernetes cluster.
 	ClusterName string
 	// Tags to attach to the real volume in the cloud provider - e.g. AWS EBS