rpcserver+routerrpc: remove payment limit

lntest/itest/lnd_multi-hop-error-propagation.go

@@ -4,6 +4,7 @@ package itest
 
 import (
 	"context"
+	"math"
 	"strings"
 	"time"
 
@@ -260,7 +261,7 @@ out:
 		// We'll send in chunks of the max payment amount. If we're
 		// about to send too much, then we'll only send the amount
 		// remaining.
-		toSend := int64(lnd.MaxPaymentMSat.ToSatoshis())
+		toSend := int64(math.MaxUint32)
 		if toSend+amtSent > amtToSend {
 			toSend = amtToSend - amtSent
 		}