We previously made the cloudproviders take on the responsibility of deleting
existing load balancers; this lets us simplify the servicecontroller logic
and also lays the groundwork for more efficient cloudprovider LB implementations
to do an in-place change on a LB.
Previously the servicecontroller would do the delete, but by having the cloudprovider
take that task on, we can later remove it from the servicecontroller, and the
cloudprovider can do something more efficient.
