SPIGOT-4534: Only call event for new chunks

nms-patches/Chunk.patch

@@ -149,7 +149,7 @@
  
 +            List<Entity> toRemove = new LinkedList<>();
              this.world.a(entityslice.stream().filter((entity) -> {
-+                if (!CraftEventFactory.doEntityAddEventCalling(this.world, entity, CreatureSpawnEvent.SpawnReason.CHUNK_GEN)) {
++                if (this.needsDecoration && !CraftEventFactory.doEntityAddEventCalling(this.world, entity, CreatureSpawnEvent.SpawnReason.CHUNK_GEN)) { // Only call for new chunks
 +                    toRemove.add(entity);
 +                    return false;
 +                }