utxonursery: within IncubateOutputs, don't mark channel as fully closed

We no longer need to mark the channel as fully closed as the
ChannelArbitrator for the channel that incubation was requested for
will handle this.

utxonursery.go

@@ -391,12 +391,6 @@ func (u *utxoNursery) IncubateOutputs(
 
 	}
 
-	// If there are no outputs to incubate for this channel, we simply mark
-	// the channel as fully closed.
-	if commOutput == nil && len(htlcOutputs) == 0 {
-		utxnLog.Infof("Channel(%s) has no outputs to incubate, "+
-			"marking fully closed.", &closeSummary.ChanPoint)
-		return u.cfg.DB.MarkChanFullyClosed(&closeSummary.ChanPoint)
 	}
 
 	utxnLog.Infof("Incubating Channel(%s) has-commit=%v, num-htlcs=%d",