### CI Link

only saw it locally

### Repro line

./gradlew ':server:test' --tests "org.elasticsearch.index.mapper.flattened.FlattenedFieldSearchTests.testCardinalityAggregation" -Dtests.seed=6E5A7D9AA8064CD5 -Dtests.locale=sr -Dtests.timezone=America/Campo_Grande -Druntime.java=18

### Does it reproduce?

Yes

### Applicable branches

master

### Failure history

_No response_

### Failure excerpt

```
REPRODUCE WITH: ./gradlew ':server:test' --tests "org.elasticsearch.index.mapper.flattened.FlattenedFieldSearchTests.testCardinalityAggregation" -Dtests.seed=EC78A8CA6F57105F -Dtests.locale=sv -Dtests.timezone=SystemV/MST7MDT -Druntime.java=18
  java.lang.AssertionError: 
    Expected: a value greater than <0L>
         but: <0L> was equal to <0L>
        at __randomizedtesting.SeedInfo.seed([EC78A8CA6F57105F:85146484AA481FC8]:0)
        at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
        at org.junit.Assert.assertThat(Assert.java:956)
        at org.junit.Assert.assertThat(Assert.java:923)
        at org.elasticsearch.index.mapper.flattened.FlattenedFieldSearchTests.assertCardinality(FlattenedFieldSearchTests.java:275)
        at org.elasticsearch.index.mapper.flattened.FlattenedFieldSearchTests.testCardinalityAggregation(FlattenedFieldSearchTests.java:249)
```

Reproduces every time for me locally. Will mute.

server/src/test/java/org/elasticsearch/index/mapper/flattened/FlattenedFieldSearchTests.java
@Before
    public void setUpIndex() throws IOException {
        XContentBuilder mapping = XContentFactory.jsonBuilder()
            .startObject()
            .startObject("_doc")
            .startObject("properties")
            .startObject("flattened")
            .field("type", "flattened")
            .field("split_queries_on_whitespace", true)
            .endObject()
            .startObject("headers")
            .field("type", "flattened")
            .field("split_queries_on_whitespace", true)
            .endObject()
            .startObject("labels")
            .field("type", "flattened")
            .endObject()
            .endObject()
            .endObject()
            .endObject();
        createIndex("test", Settings.EMPTY, mapping);
    }
    public void testMatchQuery() throws Exception {
        client().prepareIndex("test")
            .setId("1")
            .setRefreshPolicy(RefreshPolicy.IMMEDIATE)