Remove outdated predefined in json_factory

Author: TheMarex

include/engine/api/json_factory.hpp

@@ -103,8 +103,6 @@ util::json::Object makeWaypoint(const util::Coordinate &location,
                                 std::string name,
                                 const Hint &hint);
 
-util::json::Object makeRouteLeg(guidance::RouteLeg leg, util::json::Array steps);
-
 util::json::Array makeRouteLegs(std::vector<guidance::RouteLeg> legs,
                                 std::vector<util::json::Value> leg_geometries,
                                 std::vector<util::json::Value> step_geometries,