Piglin brutes do not despawn in Peaceful mode

Piglin brutes become passive in Peaceful mode instead of despawning, like in Java Edition (MC-193126).

Steps to reproduce:

1. Spawn a piglin brute
2. Go into peaceful mode

Observed result:
The piglin brute does not despawn and becomes passive instead, like regular piglins.

Expected result:
The piglin brute despawns, like in Java Edition.