Exosphere Overworld Deltas Fix

The Exosphere Generation 2.2 datapack adds nether-like features to old_growth_spruce_taiga:

• exosphere:delta — basalt delta with magma
• exosphere:small_basalt_columns + exosphere:large_basalt_columns
• minecraft:lake_lava_underground + minecraft:lake_lava_surface
• minecraft:ore_magma + minecraft:spring_delta

This datapack that overrides the biome definition with all basalt/lava/magma features removed.

All of exosphere’s tree and vegetation improvements are preserved — only the nether-like generation is stripped. This only affects newly generated chunks; existing terrain won’t change.