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
}
    public void testMinimalSearchSourceInShardRequests() {
        createIndex("test");
        int numDocs = between(0, 10);
        for (int i = 0; i < numDocs; i++) {
            client().prepareIndex("test").setSource("id", Integer.toString(i)).get();
        }
        indicesAdmin().prepareRefresh("test").get();
        String pitId = client().execute(
            OpenPointInTimeAction.INSTANCE,
            new OpenPointInTimeRequest("test").keepAlive(TimeValue.timeValueMinutes(10))
        ).actionGet().getPointInTimeId();
        final MockSearchService searchService = (MockSearchService) getInstanceFromNode(SearchService.class);
        final List<ShardSearchRequest> shardRequests = new CopyOnWriteArrayList<>();
        searchService.setOnCreateSearchContext(ctx -> shardRequests.add(ctx.request()));
        try {
            SearchRequest searchRequest = new SearchRequest().source(
                new SearchSourceBuilder().size(between(numDocs, numDocs * 2)).pointInTimeBuilder(new PointInTimeBuilder(pitId))
            );
            final SearchResponse searchResponse = client().search(searchRequest).actionGet();
            assertHitCount(searchResponse, numDocs);
        } finally {
            client().execute(ClosePointInTimeAction.INSTANCE, new ClosePointInTimeRequest(pitId)).actionGet();
        }
        assertThat(shardRequests, not(emptyList()));
        for (ShardSearchRequest shardRequest : shardRequests) {
            assertNotNull(shardRequest.source());
            assertNotNull(shardRequest.source().pointInTimeBuilder());
            assertThat(shardRequest.source().pointInTimeBuilder().getEncodedId(), equalTo(""));
        }