(Since only few maps support different placement patterns currently, there wouldn't be an expectation of persistance of this setting when switching maps.)
So it could be implemented using #4838. EDIT: Actually no, since this setting is shared by many maps, so it should be in gamesetup.js like the biome.
(Also this will run into the same issue of Atlas requiring a new dropdown or not being able to recreate the same map as the gamesetup can)
