This patch switches over to the payload style of callbacks by updating
neutron to callbacks to handle a DBEventPayload for BEFORE_DELETE events
of ROUTER_INTERFACE resources. See the depends on patch for more
details.
Depends-On: Idd1f43dc7a13b93d9380f49909777e129f1214f2
Change-Id: Ie39dd8cfaed56c79f8dca4ee7438bd0f6c47f32a