Use controller-runtime utility package to set and remove ownerRefs.

[guettli]

/kind feature

Currently, the code does not use controller-runtime utils to set ownerRefs.

The code should use controllerutil to set and remove OwnerReferences.

Example:

// setOwnerRef adds an owner reference of this HetznerBareMetalMachine.
func (s *Service) setOwnerRef(refList []metav1.OwnerReference) []metav1.OwnerReference {
	return setOwnerRefInList(refList, s.scope.BareMetalMachine.TypeMeta, s.scope.BareMetalMachine.ObjectMeta)
}