[Atlas] [Maps] Update the Default map in Atlas
Lowers default terrain grid height, which helps with shadow sharpness on old shadows and allows for more vertical height A nicer Skybox as default One of the new higher-quality Terrain Textures by default
Patch by: @wowgetoffyourcellphone
Accepted by: @marder
Differential Revision: https://code.wildfiregames.com/D4446