Revert "In sc.runJob, actually clean the inner closure"

This reverts commit 3998168.

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -1627,10 +1627,7 @@ class SparkContext(config: SparkConf) extends Logging with ExecutorAllocationCli
       partitions: Seq[Int],
       allowLocal: Boolean
       ): Array[U] = {
-    // We must clean `func` here before using it in another closure below
-    // Otherwise, the closure cleaner will only clean the outer closure but not `func`
-    val cleanedFunc = clean(func)
-    runJob(rdd, (ctx: TaskContext, iter: Iterator[T]) => cleanedFunc(iter), partitions, allowLocal)
+    runJob(rdd, (context: TaskContext, iter: Iterator[T]) => func(iter), partitions, allowLocal)
   }
 
   /**