Delete unused registry client fake and remove go:generate. (#2783)

This fake is unused and was removed in an earlier patch, but
apparently there was another corresponding go:generate comment that
wasn't removed.

Signed-off-by: Ben Luddy <bluddy@redhat.com>

Author: benluddy

pkg/controller/registry/registry_client.go

@@ -1,4 +1,3 @@
-//go:generate go run github.com/maxbrunsfeld/counterfeiter/v6 -o resolver/fakes/fake_registry_client_interface.go . ClientInterface
 package registry
 
 import (