[Inference API] handle retries for rate-limited non-streaming requests to the Elastic Inference Service

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elastic/ElasticInferenceServiceResponseHandler.java

@@ -40,6 +40,8 @@ protected void checkForFailureStatusCode(Request request, HttpResult result) thr
             throw new RetryException(false, buildError(METHOD_NOT_ALLOWED, request, result));
         } else if (statusCode == 413) {
             throw new ContentTooLargeException(buildError(CONTENT_TOO_LARGE, request, result));
+        } else if (statusCode == 429) {
+            throw new RetryException(true, buildError(RATE_LIMIT, request, result));
         }
 
         throw new RetryException(false, buildError(UNSUCCESSFUL, request, result));