Fix and optimize getChunkCount (#11610)

It was returning ticking chunk count instead of the intended full chunk count.
We can also directly use the size of the fullChunks collection instead of iterating all chunks.

patches/server/Provide-E-TE-Chunk-count-stat-methods.patch

@@ -60,15 +60,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +    @Override
 +    public int getChunkCount() {
-+        int ret = 0;
-+
-+        for (ChunkHolder chunkHolder : ca.spottedleaf.moonrise.common.util.ChunkSystem.getVisibleChunkHolders(this.world)) {
-+            if (chunkHolder.getTickingChunk() != null) {
-+                ++ret;
-+            }
-+        }
-+
-+        return ret;
++        return this.world.getChunkSource().getFullChunksCount();
 +    }
 +
 +    @Override