Fix incorrect keyword use on visibleChunksClone

Spigot-Server-Patches/Optimize-PlayerChunkMap-memory-use-for-visibleChunks.patch

@@ -47,7 +47,7 @@ index e1e4ea793a..0aa6487d5b 100644
      public final Long2ObjectLinkedOpenHashMap<PlayerChunk> updatingChunks = new Long2ObjectLinkedOpenHashMap();
 -    public volatile Long2ObjectLinkedOpenHashMap<PlayerChunk> visibleChunks;
 +    public final Long2ObjectLinkedOpenHashMap<PlayerChunk> visibleChunks = new Long2ObjectLinkedOpenHashMap(); // Paper - remove copying, make mt safe
-+    public transient Long2ObjectLinkedOpenHashMap<PlayerChunk> visibleChunksClone; // Paper - remove copying, make mt safe
++    public volatile Long2ObjectLinkedOpenHashMap<PlayerChunk> visibleChunksClone; // Paper - remove copying, make mt safe
      private final Long2ObjectLinkedOpenHashMap<PlayerChunk> pendingUnload;
      final LongSet loadedChunks; // Paper - private -> package
      public final WorldServer world;