Only Windows runs are failing.

**Build scan:**
https://gradle-enterprise.elastic.co/s/zyijl5succa7u/tests/:modules:data-streams:internalClusterTest/org.elasticsearch.datastreams.DataStreamIT/testWriteLoadAndAvgShardSizeIsStoredInABestEffort

**Reproduction line:**
```
gradlew ':modules:data-streams:internalClusterTest' --tests "org.elasticsearch.datastreams.DataStreamIT.testWriteLoadAndAvgShardSizeIsStoredInABestEffort" -Dtests.seed=38CC3C8574AEB1D8 -Dtests.locale=es-PA -Dtests.timezone=Pacific/Tongatapu -Druntime.java=19
```

**Applicable branches:**
8.6, main

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.datastreams.DataStreamIT&tests.test=testWriteLoadAndAvgShardSizeIsStoredInABestEffort

**Failure excerpt:**
```
java.lang.AssertionError: 
Expected: is not null
     but: was null

  at __randomizedtesting.SeedInfo.seed([38CC3C8574AEB1D8:9CF0E198064B4DB3]: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.datastreams.DataStreamIT.testWriteLoadAndAvgShardSizeIsStoredInABestEffort(DataStreamIT.java:2113)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
  at java.lang.reflect.Method.invoke(Method.java:578)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:44)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:1589)

```
modules/data-streams/src/internalClusterTest/java/org/elasticsearch/datastreams/DataStreamIT.java
assertThat(e.getCause().getMessage(), equalTo("data stream timestamp field [@timestamp] encountered multiple values"));
    }
    public void testMixedAutoCreate() throws Exception {
        PutComposableIndexTemplateAction.Request createTemplateRequest = new PutComposableIndexTemplateAction.Request("logs-foo");
        createTemplateRequest.indexTemplate(
            new ComposableIndexTemplate(
                List.of("logs-foo*"),
                new Template(null, new CompressedXContent(generateMapping("@timestamp")), null),
                null,
                null,
                null,
                null,
                new ComposableIndexTemplate.DataStreamTemplate(),
                null
            )
        );
        client().execute(PutComposableIndexTemplateAction.INSTANCE, createTemplateRequest).actionGet();
        BulkRequest bulkRequest = new BulkRequest();
        bulkRequest.add(new IndexRequest("logs-foobar").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkRequest.add(new IndexRequest("logs-foobaz").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkRequest.add(new IndexRequest("logs-barbaz").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkRequest.add(new IndexRequest("logs-barfoo").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        BulkResponse bulkResponse = client().bulk(bulkRequest).actionGet();
        assertThat("bulk failures: " + Strings.toString(bulkResponse), bulkResponse.hasFailures(), is(false));
        bulkRequest = new BulkRequest();
        bulkRequest.add(new IndexRequest("logs-foobar").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkRequest.add(new IndexRequest("logs-foobaz2").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkRequest.add(new IndexRequest("logs-barbaz").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkRequest.add(new IndexRequest("logs-barfoo2").opType(CREATE).source("{\"@timestamp\": \"2020-12-12\"}", XContentType.JSON));
        bulkResponse = client().bulk(bulkRequest).actionGet();