upr-notifier stream hangs when start_seq >0 and vb_uuid is missing

NotifierStreams are protected from rollback by setting high_seqno to start_seqno.
This causes needRollback in in failover-table.cc to always return false.

Problem is this will skip case where vb_uuid doesn't not exist in failovertable, because under normal cases producer stream requests returns rollback when client tries to stream mutations past seqno 0 when vbuuid does not exist.

Result is that notifier stream is created, but is never notified of stream_end because it is not subscribed to any vbucket.