[SPARK-3974] Updated testing utils from master

Author: brkyvz

mllib/src/test/scala/org/apache/spark/mllib/linalg/distributed/BlockMatrixSuite.scala

@@ -22,9 +22,9 @@ import org.scalatest.FunSuite
 import breeze.linalg.{DenseMatrix => BDM}
 
 import org.apache.spark.mllib.linalg.{DenseMatrix, Matrices}
-import org.apache.spark.mllib.util.LocalSparkContext
+import org.apache.spark.mllib.util.MLlibTestSparkContext
 
-class BlockMatrixSuite extends FunSuite with LocalSparkContext {
+class BlockMatrixSuite extends FunSuite with MLlibTestSparkContext {
 
   val m = 5
   val n = 4