Do not attach temporary wagons to free wagon chains when autoreplacing

See: https://github.com/OpenTTD/OpenTTD/issues/9264

src/train_cmd.cpp

@@ -1929,7 +1929,7 @@ CommandCost CmdMoveRailVehicle(TileIndex tile, DoCommandFlag flags, uint32 p1, u
 	/* if nothing is selected as destination, try and find a matching vehicle to drag to. */
 	Train *dst;
 	if (d == INVALID_VEHICLE) {
-		dst = src->IsEngine() ? nullptr : FindGoodVehiclePos(src);
+		dst = (src->IsEngine() || (flags & DC_AUTOREPLACE)) ? nullptr : FindGoodVehiclePos(src);
 	} else {
 		dst = Train::GetIfValid(d);
 		if (dst == nullptr) return check_on_failure(CMD_ERROR);