default compression level change (opensearch-project#8471)

Signed-off-by: Sarthak Aggarwal <sarthagg@amazon.com>

Author: sarthakaggarwal97

CHANGELOG.md

@@ -152,6 +152,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add self-organizing hash table to improve the performance of bucket aggregations ([#7652](https://github.com/opensearch-project/OpenSearch/pull/7652))
 - Check UTF16 string size before converting to String to avoid OOME ([#7963](https://github.com/opensearch-project/OpenSearch/pull/7963))
 - Move ZSTD compression codecs out of the sandbox ([#7908](https://github.com/opensearch-project/OpenSearch/pull/7908))
+- Update ZSTD default compression level ([#8471](https://github.com/opensearch-project/OpenSearch/pull/8471))
 
 
 ### Deprecated

server/src/main/java/org/opensearch/index/codec/customcodecs/Lucene95CustomCodec.java

@@ -23,7 +23,7 @@
  * @opensearch.internal
  */
 public abstract class Lucene95CustomCodec extends FilterCodec {
-    public static final int DEFAULT_COMPRESSION_LEVEL = 6;
+    public static final int DEFAULT_COMPRESSION_LEVEL = 3;
 
     /** Each mode represents a compression algorithm. */
     public enum Mode {