multi: rename FailUnknownPaymentHash to FailIncorrectDetails

Align naming better with the lightning spec. Not the full name of the
failure (FailIncorrectOrUnknownPaymentDetails) is used, because this
would cause too many long lines in the code.

routing/missioncontrol_store_test.go

@@ -59,7 +59,7 @@ func TestMissionControlStore(t *testing.T) {
 
 	result1 := paymentResult{
 		route:            &testRoute,
-		failure:          lnwire.NewFailUnknownPaymentHash(100),
+		failure:          lnwire.NewFailIncorrectDetails(100),
 		failureSourceIdx: &failureSourceIdx,
 		id:               99,
 		timeReply:        testTime,