### CI Link

https://gradle-enterprise.elastic.co/s/pzjicoqh7nuhq

### Repro line

./gradlew ':server:internalClusterTest' --tests "org.elasticsearch.snapshots.BlobStoreIncrementalityIT.testRecordCorrectSegmentCountsWithBackgroundMerges" -Dtests.seed=DEA1040A4A18200C -Dtests.locale=ar-KW -Dtests.timezone=Etc/Universal -Druntime.java=17

### Does it reproduce?

Yes

### Applicable branches

main, 8.4

### Failure history

First time it fails in the last 7 days: https://gradle-enterprise.elastic.co/scans/tests?search.timeZoneId=Europe/Bucharest&tests.container=org.elasticsearch.snapshots.BlobStoreIncrementalityIT&tests.test=testRecordCorrectSegmentCountsWithBackgroundMerges

### Failure excerpt

```
org.elasticsearch.snapshots.BlobStoreIncrementalityIT > testRecordCorrectSegmentCountsWithBackgroundMerges FAILED
    java.lang.AssertionError: 
    Expected: a value less than <3L>
         but: <3L> was equal to <3L>
        at __randomizedtesting.SeedInfo.seed([DEA1040A4A18200C:C81912C0892C8B7B]: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.snapshots.BlobStoreIncrementalityIT.lambda$testRecordCorrectSegmentCountsWithBackgroundMerges$0(BlobStoreIncrementalityIT.java:236)
        at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:1104)
        at org.elasticsearch.snapshots.BlobStoreIncrementalityIT.testRecordCorrectSegmentCountsWithBackgroundMerges(BlobStoreIncrementalityIT.java:234)
```
server/src/internalClusterTest/java/org/elasticsearch/snapshots/BlobStoreIncrementalityIT.java
import org.elasticsearch.action.admin.indices.stats.IndexStats;
import org.elasticsearch.action.admin.indices.stats.IndicesStatsResponse;
import org.elasticsearch.action.bulk.BulkItemResponse;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkRequestBuilder;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.support.WriteRequest;
import org.elasticsearch.client.internal.Requests;
import org.elasticsearch.cluster.metadata.IndexMetadata;
import org.elasticsearch.cluster.routing.UnassignedInfo;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.util.CollectionUtils;
import org.elasticsearch.index.MergePolicyConfig;
import org.elasticsearch.plugins.Plugin;
import org.elasticsearch.test.ESIntegTestCase;
import org.elasticsearch.test.InternalSettingsPlugin;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailures;
import static org.elasticsearch.xcontent.XContentFactory.jsonBuilder;
import static org.hamcrest.Matchers.greaterThan;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.lessThan;
@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0)