Giving provision to operators to configure RPC topic for
masakari-engine service can lead to some errors pointed by the
bug: 1643834. So there is no need to let operators choose the RPC
topic for engine service. It's best to deprecate and remove this
option as it's really easy to break masakari by using this option,
and there is little gain for deployers in changing this option.
Change-Id: Ie8e55762201cbf69f90838217098860ded51a307
Dinesh Bhor