Remove getUnloadingChunkHolder check

It always returns null now. So it could NPE and is not useful.

patches/server/1027-Fix-CraftWorld-isChunkGenerated.patch

@@ -6,10 +6,10 @@ Subject: [PATCH] Fix CraftWorld#isChunkGenerated
 The upstream implementation is returning true for non-full chunks.
 
 diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
-index fe9e8d1d4ae1f7a4e8f4cf5688004fc969422b3c..b466a1edaa6c1123dedda8376eabc3be0a011874 100644
+index fe9e8d1d4ae1f7a4e8f4cf5688004fc969422b3c..95de729f0a02a202632ea85a4061607d632588e9 100644
 --- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 +++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
-@@ -367,11 +367,30 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+@@ -367,11 +367,27 @@ public class CraftWorld extends CraftRegionAccessor implements World {
  
      @Override
      public boolean isChunkGenerated(int x, int z) {
@@ -24,9 +24,6 @@ index fe9e8d1d4ae1f7a4e8f4cf5688004fc969422b3c..b466a1edaa6c1123dedda8376eabc3be
 +            }, world.getChunkSource().mainThreadProcessor).join();
 +        }
 +        ChunkAccess chunk = world.getChunkSource().getChunkAtImmediately(x, z);
-+        if (chunk == null) {
-+            chunk = world.getChunkSource().chunkMap.getUnloadingChunkHolder(x, z).getLatestChunk();
-+        }
 +        if (chunk != null) {
 +            return chunk instanceof ImposterProtoChunk || chunk instanceof net.minecraft.world.level.chunk.LevelChunk;
          }