Remove unused code.

- all these were replaced by the modify_transaction method
ServiceDashboardClientDiffer accepts dashboard clients, not catalog services

-dashboard client differ should not know anything about catalogs
Move dashboard client delete logic into ServiceDashboardClientManager

- now that we use the uaa transactional endpoint, the logic for making
  CC claims and modifying clients on uaa is always the same. move it to
  the object that should know how to do that.