Support PVC expansion with the local-path provisioner.

[HoustonPutman]

The failure of "Expanding PVCs" in KinD clusters was first documented in #1716 . And at that time the Local Storage Provisioner "did not support volume expansion". However, shortly after it was discussed in https://github.com/rancher/local-path-provisioner/pull/189, and afterwards the default storage class created for the provisioner had allowVolumeExpansion: true.

Since KinD creates its own storage class, instead of using the Helm Chart provided by the local-path-provisioner project, the storageClass must be updated here as well to support volume expansion. (Which the local path provisioner supports, because it doesn't actually place any limits on volume sizes in the first place)