[SPARK-7420][STREAMING][TESTS] Enable test: o.a.s.streaming.JobGeneratorSuite...

[SPARK-7420][STREAMING][TESTS] Enable test: o.a.s.streaming.JobGeneratorSuite "Do not clear received…

## How was this patch tested?

unit test

Author: proflin <proflin.me@gmail.com>

Closes #11626 from lw-lin/SPARK-7420.

streaming/src/test/scala/org/apache/spark/streaming/scheduler/JobGeneratorSuite.scala

@@ -56,8 +56,7 @@ class JobGeneratorSuite extends TestSuiteBase {
   // 4. allow subsequent batches to be generated (to allow premature deletion of 3rd batch metadata)
   // 5. verify whether 3rd batch's block metadata still exists
   //
-  // TODO: SPARK-7420 enable this test
-  ignore("SPARK-6222: Do not clear received block data too soon") {
+  test("SPARK-6222: Do not clear received block data too soon") {
     import JobGeneratorSuite._
     val checkpointDir = Utils.createTempDir()
     val testConf = conf