**Build scan:**
https://gradle-enterprise.elastic.co/s/efbbdu2lrerh6/tests/:x-pack:plugin:ml:test/org.elasticsearch.xpack.ml.dataframe.traintestsplit.StratifiedTrainTestSplitterTests/testIsTraining_SelectsTrainingRowsUniformly

**Reproduction line:**
```
./gradlew ':x-pack:plugin:ml:test' --tests "org.elasticsearch.xpack.ml.dataframe.traintestsplit.StratifiedTrainTestSplitterTests.testIsTraining_SelectsTrainingRowsUniformly" -Dtests.seed=49990582BF0D1A3A -Dtests.locale=sq -Dtests.timezone=Antarctica/Vostok -Druntime.java=17
```

**Applicable branches:**
8.5, 8.6, main

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.ml.dataframe.traintestsplit.StratifiedTrainTestSplitterTests&tests.test=testIsTraining_SelectsTrainingRowsUniformly

**Failure excerpt:**
```
java.lang.AssertionError: 
Expected: is a numeric value within <0.13> of <0.5>
     but: <0.632> differed by <0.0020000000000000018> more than delta <0.13>

  at __randomizedtesting.SeedInfo.seed([49990582BF0D1A3A:15B9681374B9DD95]: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.xpack.ml.dataframe.traintestsplit.StratifiedTrainTestSplitterTests.testIsTraining_SelectsTrainingRowsUniformly(StratifiedTrainTestSplitterTests.java:217)
  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: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:833)

```
x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/dataframe/traintestsplit/StratifiedTrainTestSplitterTests.java
int classTrainingCount = trainingRowsPerClass.get(classValue);
            assertThat((double) classTrainingCount, is(closeTo(expectedClassTrainingCount, 1.0)));
        }
    }
    public void testIsTraining_SelectsTrainingRowsUniformly() {
        double trainingPercent = 50.0;
        int runCount = 500;
        int[] trainingCountPerRow = new int[ROWS_COUNT];
        for (int run = 0; run < runCount; run++) {
            randomizeSeed = randomLong();
            TrainTestSplitter trainTestSplitter = createSplitter(trainingPercent);
            for (int i = 0; i < classValuesPerRow.length; i++) {
                String[] row = new String[fields.size()];
                for (int fieldIndex = 0; fieldIndex < fields.size(); fieldIndex++) {
                    String value = fieldIndex == dependentVariableIndex ? classValuesPerRow[i] : randomAlphaOfLength(10);
                    row[fieldIndex] = value;
                }
                String[] processedRow = Arrays.copyOf(row, row.length);
                boolean isTraining = trainTestSplitter.isTraining(processedRow);
                assertThat(Arrays.equals(processedRow, row), is(true));
                if (isTraining) {
                    trainingCountPerRow[i]++;
                }
            }
        }
        
        
        
        for (int rowTrainingCount : trainingCountPerRow) {
            double meanCount = rowTrainingCount / (double) runCount;