Load route from ID needs multiplexing support #2
Description
Currently, loading a route from an ID, in loadRouteFromId does three separate calls from journey.retrieve which is inefficient:
https://github.com/cyclestreets/routing-ui/blob/master/js/routing.js#L2203-L2219
This should be replaced with multiplexing support when _settings.multiplexedStrategies is enabled, as in loadRoute:
https://github.com/cyclestreets/routing-ui/blob/master/js/routing.js#L2253-L2256