Fix JVM deoptimization loop due to lambda misprediction (opensearch-project#20832)

---------

Signed-off-by: Christopher Peck <peck@uber.com>

Author: itschrispeck

server/src/main/java/org/opensearch/action/bulk/BulkItemRequest.java

@@ -139,7 +139,9 @@ public void writeTo(StreamOutput out) throws IOException {
     public void writeThin(StreamOutput out) throws IOException {
         out.writeVInt(id);
         DocWriteRequest.writeDocumentRequestThin(out, request);
-        out.writeOptionalWriteable(primaryResponse == null ? null : primaryResponse::writeThin);
+
+        BulkItemResponse primaryResponse = this.primaryResponse; // Read volatile once
+        out.writeOptionalWriteable((o, resp) -> resp.writeThin(o), primaryResponse);
     }
 
     @Override