fix roundabout handling with lanes

instead of artificially removing lanes from a roundabout, we don't assing them in the first place.
this also prevents a problem where we would end up collapsing turns with lanes in a roundabout

include/engine/guidance/lane_processing.hpp

@@ -22,10 +22,6 @@ OSRM_ATTR_WARN_UNUSED
 std::vector<RouteStep> anticipateLaneChange(std::vector<RouteStep> steps,
                                             const double min_duration_needed_for_lane_change = 15);
 
-// Remove all lane information from roundabouts. See #2626.
-OSRM_ATTR_WARN_UNUSED
-std::vector<RouteStep> removeLanesFromRoundabouts(std::vector<RouteStep> steps);
-
 } // namespace guidance
 } // namespace engine
 } // namespace osrm