This failed on my PR. But reproducible on master.

**Build scan:**
https://gradle-enterprise.elastic.co/s/b4dxexcgaqgxe/tests/:x-pack:plugin:ml:test/org.elasticsearch.xpack.ml.aggs.categorization2.InternalCategorizationAggregationTests/testReduceRandom

**Reproduction line:**
`./gradlew ':x-pack:plugin:ml:test' --tests "org.elasticsearch.xpack.ml.aggs.categorization2.InternalCategorizationAggregationTests.testReduceRandom" -Dtests.seed=E710873699BF25DB -Dtests.locale=cs -Dtests.timezone=Australia/Victoria -Druntime.java=17`

**Applicable branches:**
master

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.ml.aggs.categorization2.InternalCategorizationAggregationTests&tests.test=testReduceRandom

**Failure excerpt:**
```
java.lang.IllegalArgumentException: threshold must be between 0.01 and 0.99: got 1.0

  at __randomizedtesting.SeedInfo.seed([E710873699BF25DB:272D2B27BFE2BC8D]:0)
  at org.elasticsearch.xpack.ml.aggs.categorization2.TokenListCategorizer.<init>(TokenListCategorizer.java:82)
  at org.elasticsearch.xpack.ml.aggs.categorization2.InternalCategorizationAggregation.reduce(InternalCategorizationAggregation.java:270)
  at org.elasticsearch.test.InternalAggregationTestCase.testReduceRandom(InternalAggregationTestCase.java:473)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
  at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:568)
  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:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:824)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:475)
  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:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:831)
  at java.lang.Thread.run(Thread.java:833)

```
x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/aggs/categorization2/InternalCategorizationAggregationTests.java
protected List<NamedXContentRegistry.Entry> getNamedXContents() {
        return CollectionUtils.appendToCopy(
            super.getNamedXContents(),
            new NamedXContentRegistry.Entry(
                Aggregation.class,
                new ParseField(CategorizeTextAggregationBuilder.NAME),
                (p, c) -> ParsedCategorization.fromXContent(p, (String) c)
            )
        );
    }
    @Override
    protected void assertReduced(InternalCategorizationAggregation reduced, List<InternalCategorizationAggregation> inputs) {
        Map<Object, Long> reducedCounts = toCounts(reduced.getBuckets().stream());
        Map<Object, Long> totalCounts = toCounts(inputs.stream().map(InternalCategorizationAggregation::getBuckets).flatMap(List::stream));
        Map<Object, Long> expectedReducedCounts = new HashMap<>(totalCounts);
        expectedReducedCounts.keySet().retainAll(reducedCounts.keySet());
        assertThat(reducedCounts, equalTo(expectedReducedCounts));
    }
    @Override
    protected Predicate<String> excludePathsFromXContentInsertion() {
        return p -> p.contains("key");
    }
    @Override
    protected InternalCategorizationAggregation createTestInstance(
        String name,
        Map<String, Object> metadata,
        InternalAggregations aggregations
    ) {
        List<InternalCategorizationAggregation.Bucket> buckets = new ArrayList<>();
        final int numBuckets = randomNumberOfBuckets();