increase to 8

Author: iverase

server/src/main/java/org/elasticsearch/index/codec/vectors/DefaultIVFVectorsReader.java

@@ -41,7 +41,7 @@
 public class DefaultIVFVectorsReader extends IVFVectorsReader implements OffHeapStats {
 
     // How many extra centroids we need to collect for each visited centroid for hierarchical centroids.
-    public static final float CENTROID_OVERSAMPLING = 5.0f;
+    public static final float CENTROID_OVERSAMPLING = 8.0f;
 
     public DefaultIVFVectorsReader(SegmentReadState state, FlatVectorsReader rawVectorsReader) throws IOException {
         super(state, rawVectorsReader);