[ML] relaxing parameters on stratified split test (#54127)

Relaxing the error rate a bit on two of the tests.
Ran 1000s of times locally and never had a failure after these changes. 

closes https://github.com/elastic/elasticsearch/issues/54122

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/dataframe/process/crossvalidation/StratifiedCrossValidationSplitterTests.java

@@ -179,8 +179,8 @@ public class StratifiedCrossValidationSplitterTests extends ESTestCase {
 
         double expectedTotalTrainingCount = ROWS_COUNT * trainingFraction;
         assertThat(trainingDocsCount + testDocsCount, equalTo((long) ROWS_COUNT));
-        assertThat(trainingDocsCount, greaterThanOrEqualTo((long) Math.floor(expectedTotalTrainingCount - 1)));
-        assertThat(trainingDocsCount, lessThanOrEqualTo((long) Math.ceil(expectedTotalTrainingCount + 1)));
+        assertThat(trainingDocsCount, greaterThanOrEqualTo((long) (expectedTotalTrainingCount - 2)));
+        assertThat(trainingDocsCount, lessThanOrEqualTo((long) Math.ceil(expectedTotalTrainingCount) + 2));
 
         for (String classValue : classCardinalities.keySet()) {
             double expectedClassTrainingCount = totalRowsPerClass.get(classValue) * trainingFraction;
@@ -221,7 +221,7 @@ public class StratifiedCrossValidationSplitterTests extends ESTestCase {
         // should be close to the training percent, which is set to 0.5
         for (int rowTrainingCount : trainingCountPerRow) {
             double meanCount = rowTrainingCount / (double) runCount;
-            assertThat(meanCount, is(closeTo(0.5, 0.1)));
+            assertThat(meanCount, is(closeTo(0.5, 0.12)));
         }
     }