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
assertThat(Thread.currentThread().getName(), startsWith("elasticsearch[node_s_0][search_throttled]"));
                    } else {
                        assertThat(Thread.currentThread().getName(), startsWith("elasticsearch[node_s_0][search]"));
                    }
                }
                @Override
                public void onQueryPhase(SearchContext context, long tookInNanos) {
                    if ("throttled_threadpool_index".equals(context.indexShard().shardId().getIndex().getName())) {
                        assertThat(Thread.currentThread().getName(), startsWith("elasticsearch[node_s_0][search_throttled]"));
                    } else {
                        assertThat(Thread.currentThread().getName(), startsWith("elasticsearch[node_s_0][search]"));
                    }
                }
            });
        }
    }
    @Override
    protected Settings nodeSettings() {
        return Settings.builder().put("search.default_search_timeout", "5s").build();
    }
    public void testClearOnClose() {
        createIndex("index");
        client().prepareIndex("index").setId("1").setSource("field", "value").setRefreshPolicy(IMMEDIATE).get();
        SearchResponse searchResponse = client().prepareSearch("index").setSize(1).setScroll("1m").get();
        assertThat(searchResponse.getScrollId(), is(notNullValue()));
        SearchService service = getInstanceFromNode(SearchService.class);
        assertEquals(1, service.getActiveContexts());
        service.doClose(); 
        assertEquals(0, service.getActiveContexts());
    }