prow.sh: flexible test driver config
prow.sh: flexible test driver config

By moving the code into a separate function, other CSI drivers have a
chance to overwrite it. For the hostpath driver itself we need the
ability to set the driver name depending on which revision is getting
installed.

kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-lib-utils,kubernetes-csi/external-attacher-csi,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-driver-nfs