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/api/route_api.hpp

@@ -159,7 +159,6 @@ class RouteAPI : public BaseAPI
                                                               leg_geometry,
                                                               phantoms.source_phantom,
                                                               phantoms.target_phantom);
-                leg.steps = guidance::removeLanesFromRoundabouts(std::move(leg.steps));
                 leg.steps = guidance::anticipateLaneChange(std::move(leg.steps));
                 leg.steps = guidance::collapseUseLane(std::move(leg.steps));
                 leg_geometry = guidance::resyncGeometry(std::move(leg_geometry), leg.steps);

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