[MC-174329] On nether-biomed superflat or buffet worlds piglins still change to zombified piglins

On nether-biomed superflat or buffet worlds piglins change to zombified piglins right after spawning.

This is probably due to piglins checking dimension instead of biome when turning into zombified piglin.

Linked issues

They also still convert if they have the tag "isImmuneToZombification" true, which means that that tag checks biomes instead of dimensions.

@Robotic: This tag is case sensitive:

/summon minecraft:piglin ~ ~ ~ {IsImmuneToZombification:1b}