routing: move default cltv assignment out of router

This commit lifts default setting up to the rpc server level, in line
with other payment defaults.

rpcserver.go

@@ -2998,7 +2998,11 @@ func extractPaymentIntent(rpcPayReq *rpcPaymentRequest) (rpcPaymentIntent, error
 		rpcPayReq.FeeLimit, payIntent.msat,
 	)
 
-	payIntent.cltvDelta = uint16(rpcPayReq.FinalCltvDelta)
+	if rpcPayReq.FinalCltvDelta != 0 {
+		payIntent.cltvDelta = uint16(rpcPayReq.FinalCltvDelta)
+	} else {
+		payIntent.cltvDelta = zpay32.DefaultFinalCLTVDelta
+	}
 
 	// If the user is manually specifying payment details, then the payment
 	// hash may be encoded as a string.
@@ -3069,6 +3073,7 @@ func (r *rpcServer) dispatchPaymentIntent(
 		payment := &routing.LightningPayment{
 			Target:            payIntent.dest,
 			Amount:            payIntent.msat,
+			FinalCLTVDelta:    payIntent.cltvDelta,
 			FeeLimit:          payIntent.feeLimit,
 			CltvLimit:         payIntent.cltvLimit,
 			PaymentHash:       payIntent.rHash,
@@ -3077,12 +3082,6 @@ func (r *rpcServer) dispatchPaymentIntent(
 			PaymentRequest:    payIntent.payReq,
 		}
 
-		// If the final CLTV value was specified, then we'll use that
-		// rather than the default.
-		if payIntent.cltvDelta != 0 {
-			payment.FinalCLTVDelta = &payIntent.cltvDelta
-		}
-
 		preImage, route, routerErr = r.server.chanRouter.SendPayment(
 			payment,
 		)