Fix ChangePolicyforIndexIT.testChangePolicyForIndex (#75003) (#75020)

The `check-rollover-ready` step is subject to the refresh making the
doc count stats available. The `refresh` execution is not deterministic
(especially for indices that are not queried) so the index might end up
staying in the `hot` phase and failing the test.

This triggers the refresh when writting to the index.

Co-authored-by: Andrei Dan <[email protected]>

Author: elasticsearchmachine

x-pack/plugin/ilm/qa/multi-node/src/javaRestTest/java/org/elasticsearch/xpack/ilm/ChangePolicyforIndexIT.java

@@ -14,8 +14,8 @@
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.test.rest.ESRestTestCase;
 import org.elasticsearch.xpack.core.ilm.AllocateAction;
 import org.elasticsearch.xpack.core.ilm.LifecyclePolicy;
@@ -111,7 +111,7 @@ public void testChangePolicyForIndex() throws Exception {
         XContentBuilder document = jsonBuilder().startObject();
         document.field("foo", "bar");
         document.endObject();
-        final Request request = new Request("POST", "/" + indexName + "/_doc/1");
+        final Request request = new Request("POST", "/" + indexName + "/_doc/1?refresh");
         request.setJsonEntity(Strings.toString(document));
         assertOK(client().performRequest(request));