[Backport to 2.x] Fix flaky integ test caused by latency of undeploy …

…model (opensearch-project#345) (opensearch-project#352)

Signed-off-by: zane-neo <[email protected]>

src/test/java/org/opensearch/neuralsearch/common/BaseNeuralSearchIT.java

@@ -576,7 +576,10 @@ protected void deleteModel(String modelId) {
             toHttpEntity(""),
             ImmutableList.of(new BasicHeader(HttpHeaders.USER_AGENT, DEFAULT_USER_AGENT))
         );
-        Thread.sleep(DEFAULT_TASK_RESULT_QUERY_INTERVAL_IN_MILLISECOND);
+
+        // after model undeploy returns, the max interval to update model status is 3s in ml-commons CronJob.
+        Thread.sleep(3000);
+
         makeRequest(
             client(),
             "DELETE",