Fix occasional SearchServiceTests failure (#39697)

Currently SearchServiceTests.testCloseSearchContextOnRewriteException can fail
if a refresh happens while we test for the SearchPhaseExecutionException that is
thrown later in the test. The test takes the current Store#refCount and expects
it to be the same after the exception is thrown. If a refresh happens in that
interval however, the refCound will be different, causing the test to fail. This
can be provoked e.g. by running this section in a tight loop.
Switching of refresh for this tests solves the issue.

Author: Christoph Büscher

server/src/test/java/org/elasticsearch/search/SearchServiceTests.java

@@ -19,6 +19,7 @@
 package org.elasticsearch.search;
 
 import com.carrotsearch.hppc.IntArrayList;
+
 import org.apache.lucene.search.Query;
 import org.apache.lucene.store.AlreadyClosedException;
 import org.elasticsearch.ElasticsearchException;
@@ -198,7 +199,8 @@ public void testClearIndexDelete() {
     }
 
     public void testCloseSearchContextOnRewriteException() {
-        createIndex("index");
+        // if refresh happens while checking the exception, the subsequent reference count might not match, so we switch it off
+        createIndex("index", Settings.builder().put("index.refresh_interval", -1).build());
         client().prepareIndex("index", "type", "1").setSource("field", "value").setRefreshPolicy(IMMEDIATE).get();
 
         SearchService service = getInstanceFromNode(SearchService.class);