update the indexRandom function to create more segments and update (#10247) (#11009)

IndicesRequestCacheIT, HighlighterSearcherIT to run with minimum of 2
slices

Signed-off-by: Neetika Singhal <neetiks@amazon.com>
(cherry picked from commit bc74731)

Author: neetikasinghal

CHANGELOG.md

@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Added cluster setting cluster.restrict.index.replication_type to restrict setting of index setting replication type ([#10866](https://github.com/opensearch-project/OpenSearch/pull/10866))
 - Add cluster state stats ([#10670](https://github.com/opensearch-project/OpenSearch/pull/10670))
 - [Remote cluster state] Restore cluster state version during remote state auto restore ([#10853](https://github.com/opensearch-project/OpenSearch/pull/10853))
+- Update the indexRandom function to create more segments for concurrent search tests ([10247](https://github.com/opensearch-project/OpenSearch/pull/10247))
 
 ### Dependencies
 - Bumps jetty version to 9.4.52.v20230823 to fix GMS-2023-1857 ([#9822](https://github.com/opensearch-project/OpenSearch/pull/9822))

server/src/internalClusterTest/java/org/opensearch/indices/IndicesRequestCacheIT.java

@@ -539,7 +539,7 @@ public void testCanCache() throws Exception {
         assertCacheState(client, "index", 0, 4);
     }
 
-    public void testCacheWithFilteredAlias() {
+    public void testCacheWithFilteredAlias() throws InterruptedException {
         Client client = client();
         Settings settings = Settings.builder()
             .put(IndicesRequestCache.INDEX_CACHE_REQUEST_ENABLED_SETTING.getKey(), true)
@@ -562,6 +562,8 @@ public void testCacheWithFilteredAlias() {
         OpenSearchAssertions.assertAllSuccessful(forceMergeResponse);
         refresh();
 
+        indexRandomForConcurrentSearch("index");
+
         assertCacheState(client, "index", 0, 0);
 
         SearchResponse r1 = client.prepareSearch("index")