prevent oshan hotspots from spawning directly under the station

[Kamades]

Recent Oshan Round on 3 - we had THREE hotspots drift into arrivals within a few minutes of roundstart, then start overlapping and we spent a solid half the shift un-screwing arrivals\customs area.

I don't think they were inside the station on roundstart, but based on their trajectories + timing, they had to have been at most 3 tiles outside of Radio or Arrival at round start.  Made lowpop pretty... FUN for the engineer and almost killed people on arrival.