Mines occasionally spawn hordes of miner zs across several map tiles about cataclysm-dda

[PatrikLundell]

This may be caused by the same bugs as #74697, in which case it should be fixed by #74703. However, I should try to test that.

Edit:
The JSON files specifies that zombie miners can spawn outside the fenced area (a one tile wide strip along the side fence). Thus, that part is as defined (whether that's desirable is a different matter). Haven't gotten any hordes yet, but will continue trying.

[PatrikLundell]

/Confirmed

The hordes at the surface is a separate problem from that #74703 addressed, as it appears with that code as well.

What I think is happening is that the miners that should be in the tunnels end up on the surface, which is basically the opposite of the problem that PR addressed. Oddly enough, a small number of zombies are still found in the tunnels.