[1.16.5-v25] FastLeafDecay deadlocks the game when creating a second world

[TelepathicGrunt]

Thread dump: https://paste.ee/p/9jiq3

To reproduce, download this modpack: https://www.curseforge.com/minecraft/modpacks/dragonheart-cpe

Then create a world using this seed: -3075103054395883639

Exit that world and re-create the world. The game will go up to 100% and stop there forever. When doing a threadump, it shows the server thread stuck waiting on FastLeafDecay's code as the cause. I did not extensively test this so I do not know if this occurs with FastLeafDecay by itself but it might still be worth looking into.