Use our non-TypeMeta based GVK method for objectRef. (#3942)
Use our non-TypeMeta based GVK method for objectRef. (#3942)

This switches the `objectRef` function in the Route controller to leverage
the GetGroupVersionKind method we expose on our types (for synthesizing
OwnerReferences) to avoid needing to pass in a GVK.
knative/serving,knative/serving