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
static final String DUMMY_SCRIPT = "dummyScript";
        @Override
        protected Map<String, Function<Map<String, Object>, Object>> pluginScripts() {
            return Collections.singletonMap(DUMMY_SCRIPT, vars -> "dummy");
        }
        @Override
        public void onIndexModule(IndexModule indexModule) {
            indexModule.addSearchOperationListener(new SearchOperationListener() {
                @Override
                public void onFetchPhase(SearchContext context, long tookInNanos) {
                    if ("throttled_threadpool_index".equals(context.indexShard().shardId().getIndex().getName())) {