[SPARK-23464][MESOS] Fix mesos cluster scheduler options double-escaping

Don't enclose --conf option value with "", as they are already escaped by shellEscape
and additional wrapping cancels out this escaping, causing driver fail to start.

This reverts commit 9b377aa [SPARK-18114].

Manual test with driver command logging added.

Author: Marcin Kurczych <[email protected]>

Author: Marcin Kurczych

resource-managers/mesos/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala

@@ -530,7 +530,7 @@ private[spark] class MesosClusterScheduler(
       .filter { case (key, _) => !replicatedOptionsBlacklist.contains(key) }
       .toMap
     (defaultConf ++ driverConf).foreach { case (key, value) =>
-      options ++= Seq("--conf", s""""$key=${shellEscape(value)}"""".stripMargin) }
+      options ++= Seq("--conf", s"$key=${shellEscape(value)}") }
 
     options
   }