SearchServiceTests.testIsParallelCollectionSupportedForResults fails intermittently

```
12:37:10 org.elasticsearch.search.SearchServiceTests > testIsParallelCollectionSupportedForResults FAILED
12:37:10     java.lang.AssertionError
12:37:10         at __randomizedtesting.SeedInfo.seed([4140C168DE8FB0BB:771A78D5E4B36180]:0)
12:37:10         at org.junit.Assert.fail(Assert.java:86)
12:37:10         at org.junit.Assert.assertTrue(Assert.java:41)
12:37:10         at org.junit.Assert.assertFalse(Assert.java:64)
12:37:10         at org.junit.Assert.assertFalse(Assert.java:74)
12:37:10         at org.elasticsearch.search.SearchServiceTests.testIsParallelCollectionSupportedForResults(SearchServiceTests.java:2096)
```

```
./gradlew ':server:test' --tests "org.elasticsearch.search.SearchServiceTests.testIsParallelCollectionSupportedForResults" -Dtests.seed=4140C168DE8FB0BB -Dtests.locale=es-SV -Dtests.timezone=Africa/Banjul -Druntime.java=20
```
server/src/test/java/org/elasticsearch/search/SearchServiceTests.java
}
            try {
                ClusterUpdateSettingsResponse response = client().admin()
                    .cluster()
                    .prepareUpdateSettings()
                    .setPersistentSettings(Settings.builder().put(SEARCH_WORKER_THREADS_ENABLED.getKey(), false).build())
                    .get();
                assertTrue(response.isAcknowledged());
                {
                    SearchContext searchContext = service.createContext(readerContext, request, task, ResultsType.DFS, randomBoolean());
                    assertNull(searchContext.searcher().getExecutor());
                }
            } finally {
                
                client().admin()
                    .cluster()
                    .prepareUpdateSettings()
                    .setPersistentSettings(Settings.builder().putNull(SEARCH_WORKER_THREADS_ENABLED.getKey()).build())
                    .get();
                SearchContext searchContext = service.createContext(readerContext, request, task, ResultsType.DFS, randomBoolean());
                assertNotNull(searchContext.searcher().getExecutor());
            }
        }
    }
    public void testEnableQueryPhaseParallelCollection() throws IOException {
        IndexService indexService = createIndex("index", Settings.EMPTY);
        IndexShard indexShard = indexService.getShard(0);
        ShardSearchRequest request = new ShardSearchRequest(
            OriginalIndices.NONE,
            new SearchRequest().allowPartialSearchResults(randomBoolean()),