[HOTFIX] Use the old Job API to support old Hadoop versions

#5526 uses `Job.getInstance`, which does not exist in the old Hadoop versions. Just use `new Job` to replace it.

cc liancheng

Author: zsxwing <zsxwing@gmail.com>

Closes #6095 from zsxwing/hotfix and squashes the following commits:

b0c2049 [zsxwing] Use the old Job API to support old Hadoop versions

sql/core/src/main/scala/org/apache/spark/sql/sources/commands.scala

@@ -88,7 +88,7 @@ private[sql] case class InsertIntoFSBasedRelation(
     }
 
     if (doInsertion) {
-      val job = Job.getInstance(hadoopConf)
+      val job = new Job(hadoopConf)
       job.setOutputKeyClass(classOf[Void])
       job.setOutputValueClass(classOf[Row])
       FileOutputFormat.setOutputPath(job, qualifiedOutputPath)