protosanitizer: test +v conversion
protosanitizer: test +v conversion

Sometimes "%+v" was used to print a message although it produces the
same output as "%v" and "%s" for gRPC messages because they implement
fmt.Stringer. It's worthwhile having a test that ensures that wrapping
the message with StripSecrets and printing with "+v" still works.

kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-lib-utils