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
final int maxPoolSize = executor.getMaximumPoolSize();
                assertEquals(
                    "Sanity check to ensure this isn't the default of 1 when pool size is unset",
                    configuredMaxPoolSize,
                    maxPoolSize
                );
                final int expectedSlices = ContextIndexSearcher.computeSlices(searcher.getIndexReader().leaves(), maxPoolSize, 1).length;
                assertNotEquals("Sanity check to ensure this isn't the default of 1 when pool size is unset", 1, expectedSlices);
                final long priorExecutorTaskCount = executor.getCompletedTaskCount();
                searcher.search(termQuery, new TotalHitCountCollectorManager());
                assertBusy(
                    () -> assertEquals(
                        "DFS supports parallel collection, so the number of slices should be > 1.",
                        expectedSlices,
                        executor.getCompletedTaskCount() - priorExecutorTaskCount
                    )
                );
            }
            {
                SearchContext searchContext = service.createContext(readerContext, request, task, ResultsType.QUERY, true);
                ContextIndexSearcher searcher = searchContext.searcher();
                assertNotNull(searcher.getExecutor());
                final long priorExecutorTaskCount = executor.getCompletedTaskCount();
                searcher.search(termQuery, new TotalHitCountCollectorManager());
                assertBusy(
                    () -> assertEquals(
                        "The number of slices should be 1 as QUERY parallel collection is disabled by default.",
                        1,
                        executor.getCompletedTaskCount() - priorExecutorTaskCount
                    )