When we get all router ids bound to edge, we now just search in
nsxv_router_bindings. But sometime there maybe inconsistency and we have
ghost router bindings left whose router db has actually been deleted.
Following shared router backend ops would unexpectly break with these ghost
router ids, worse itself also become a ghost after router db is deleted.
The patch avoids it happend by double getting router ids also from Router db.
Change-Id: If111ab8355102120d509c91e547fcde4cd309f16
64d32be67d