Break machinery objective take into account multi z stations and only assigns station machines

[ToasterBiome]

Document the changes in your pull request

• always got the lowest z level for the objective, this means that icemeta would look at the bottom most station level always
• got non-station machines too, so on icemeta you'd have to venture to random machines in the lower Z levels to a machine nobody cares about

Why is this good for the game?

More consistent + actually keeps these objectives station-side

Testing

Changelog

🆑
tweak: Break machinery objective take into account multi z stations and only assigns station machines
/:cl: