Disable use of Locks on main thread for DataPaletteBlock

This should greatly improve performance by using a No Op lock
while on the main thread.

Vanilla always had a write lock on write operations, but we added
a Read Lock during Async Chunks to make concurrent writes non fatal
for Async Chunks.

This means we added on a bunch of over head to all chunk read operations.

This corrects that, as well as disabling the write lock while on main thread.

It is a general rule that you do not touch a chunk async once it is loaded
into the world, as we never had locks on the chunk before 1.13 even.

So once we are on main, we don't expect concurrent access to begin with,
so we don't need the write locks either.

Spigot-Server-Patches/Optimize-Light-Recalculations.patch

@@ -14,7 +14,7 @@ Also optimizes to not repeatedly look up the same chunk for
 light lookups.
 
 diff --git a/src/main/java/net/minecraft/server/Chunk.java b/src/main/java/net/minecraft/server/Chunk.java
-index 9162151e2a..651bb23be9 100644
+index 15a327923f..0b2d9a05f4 100644
 --- a/src/main/java/net/minecraft/server/Chunk.java
 +++ b/src/main/java/net/minecraft/server/Chunk.java
 @@ -0,0 +0,0 @@ public class Chunk implements IChunkAccess {