Remove OpenStack cloud provider

And keep OpenStack Cinder CSI translation

test/e2e/framework/providers/openstack/openstack.go

@@ -29,6 +29,9 @@ func newProvider() (framework.ProviderInterface, error) {
 }
 
 // Provider is a structure to handle OpenStack clouds for e2e testing
+// It does not do anything useful, it's there only to provide valid
+// --provider=openstack cmdline option to allow testing of CSI migration
+// tests of kubernetes.io/cinder volume plugin.
 type Provider struct {
 	framework.NullProvider
 }