routerrpc: mark QueryProbability deprecated

We deprecate `QueryProbability`, as it displays the same information as
`QueryMissionControl` less the probability. `QueryRoutes` still contains
the total probability of a route.

lnrpc/routerrpc/router_server.go

@@ -692,47 +692,6 @@ func getMsatPairValue(msatValue lnwire.MilliSatoshi,
 		satValue)
 }
 
-// QueryProbability returns the current success probability estimate for a
-// given node pair and amount.
-func (s *Server) QueryProbability(ctx context.Context,
-	req *QueryProbabilityRequest) (*QueryProbabilityResponse, error) {
-
-	fromNode, err := route.NewVertexFromBytes(req.FromNode)
-	if err != nil {
-		return nil, err
-	}
-
-	toNode, err := route.NewVertexFromBytes(req.ToNode)
-	if err != nil {
-		return nil, err
-	}
-
-	amt := lnwire.MilliSatoshi(req.AmtMsat)
-
-	// Compute the probability.
-	var prob float64
-	mc := s.cfg.RouterBackend.MissionControl
-	capacity, err := s.cfg.RouterBackend.FetchAmountPairCapacity(
-		fromNode, toNode, amt,
-	)
-
-	// If we cannot query the capacity this means that either we don't have
-	// information available or that the channel fails min/maxHtlc
-	// constraints, so we return a zero probability.
-	if err != nil {
-		log.Errorf("Cannot fetch capacity: %v", err)
-	} else {
-		prob = mc.GetProbability(fromNode, toNode, amt, capacity)
-	}
-
-	history := mc.GetPairHistorySnapshot(fromNode, toNode)
-
-	return &QueryProbabilityResponse{
-		Probability: prob,
-		History:     toRPCPairData(&history),
-	}, nil
-}
-
 // TrackPaymentV2 returns a stream of payment state updates. The stream is
 // closed when the payment completes.
 func (s *Server) TrackPaymentV2(request *TrackPaymentRequest,