Use toStream with serialize

Signed-off-by: Finn Carroll <[email protected]>

server/src/main/java/org/opensearch/search/fetch/serde/SearchHitSerDe.java

@@ -46,7 +46,7 @@ public SearchHit deserialize(StreamInput in) {
     @Override
     public void serialize(SearchHit object, StreamOutput out) throws SerDe.SerializationException {
         try {
-            object.writeTo(out);
+            toStream(object, out);
         } catch (IOException e) {
             throw new SerDe.SerializationException("Failed to serialize FetchSearchResult", e);
         }