[HOTFIX] Hotfix branch-1.4 building by removing avgMetrics in CrossValidatorSuite

Ref. #6905
ping yhuai

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #6929 from viirya/hot_fix_cv_test and squashes the following commits:

b1aec53 [Liang-Chi Hsieh] Hotfix branch-1.4 by removing avgMetrics in CrossValidatorSuite.

Author: viirya

mllib/src/test/scala/org/apache/spark/ml/tuning/CrossValidatorSuite.scala

@@ -78,14 +78,12 @@ class CrossValidatorSuite extends SparkFunSuite with MLlibTestSparkContext {
     val parent = cvModel.bestModel.parent.asInstanceOf[LinearRegression]
     assert(parent.getRegParam === 0.001)
     assert(parent.getMaxIter === 10)
-    assert(cvModel.avgMetrics.length === lrParamMaps.length)
 
     eval.setMetricName("r2")
     val cvModel2 = cv.fit(dataset)
     val parent2 = cvModel2.bestModel.parent.asInstanceOf[LinearRegression]
     assert(parent2.getRegParam === 0.001)
     assert(parent2.getMaxIter === 10)
-    assert(cvModel2.avgMetrics.length === lrParamMaps.length)
   }
 
   test("validateParams should check estimatorParamMaps") {