[ML] Adjust assertion for job case memory usage estimates (#57882)

Since we change the memory estimates for data frame analytics jobs from worst case to a realistic case, the strict less-than assertion in the test does not hold anymore. I replaced it with a less-or-equal-than assertion.

x-pack/plugin/ml/qa/native-multi-node-tests/src/test/java/org/elasticsearch/xpack/ml/integration/ExplainDataFrameAnalyticsIT.java

@@ -24,7 +24,6 @@ import org.elasticsearch.xpack.core.ml.utils.QueryProvider;
 import java.io.IOException;
 
 import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.lessThan;
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 
 public class ExplainDataFrameAnalyticsIT extends MlNativeDataFrameAnalyticsIntegTestCase {
@@ -124,6 +123,7 @@ public class ExplainDataFrameAnalyticsIT extends MlNativeDataFrameAnalyticsInteg
 
         explainResponse = explainDataFrame(config);
 
-        assertThat(explainResponse.getMemoryEstimation().getExpectedMemoryWithoutDisk(), lessThan(allDataUsedForTraining));
+        assertThat(explainResponse.getMemoryEstimation().getExpectedMemoryWithoutDisk(), 
+                   lessThanOrEqualTo(allDataUsedForTraining));
     }
 }