[SQL] In InsertIntoFSBasedRelation.insert, log cause before abort job/task.

We need to add a log entry before calling `abortTask`/`abortJob`. Otherwise, an exception from `abortTask`/`abortJob` will shadow the real cause.

cc liancheng

Author: Yin Huai <yhuai@databricks.com>

Closes #6105 from yhuai/logCause and squashes the following commits:

8dfe0d8 [Yin Huai] Log cause.

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

@@ -121,6 +121,7 @@ private[sql] case class InsertIntoFSBasedRelation(
       writerContainer.commitJob()
       relation.refresh()
     } catch { case cause: Throwable =>
+      logError("Aborting job.", cause)
       writerContainer.abortJob()
       throw new SparkException("Job aborted.", cause)
     }
@@ -143,6 +144,7 @@ private[sql] case class InsertIntoFSBasedRelation(
         }
         writerContainer.commitTask()
       } catch { case cause: Throwable =>
+        logError("Aborting task.", cause)
         writerContainer.abortTask()
         throw new SparkException("Task failed while writing rows.", cause)
       }