Multi-Z prevents stepping onto other Z-levels from the station level (RIP space ruins)

[Yogbot-13]

Round ID: 51822

Test Merges:

#21025, #15579, #20581, #21623

Reproduction:

From my experience of trying to escape the station Z-level, I apparently became stuck at the border, with a vast darkness where the seamless transition to another Z-level would be. This was done in the top level of the currently testmerged Multi-Z gax PR.

Supplied Image:

Submitted by: amyriad (170817240223055872)