Segfault if competition is started "too early"

If the /ariac/start_competition service is called "too early" there's a crash. It's not clear which plugin is causing the crash, but I suspect it is the PopulationPlugin trying to teleport a model that hasn't been fully loaded yet.

Anecdotally it seems it can be avoided by waiting until the RTF starts climbing/stabilises after the world is brought up.