[SPARK-18960][SQL][SS] Avoid double reading file which is being copied.

## What changes were proposed in this pull request?

In HDFS, when we copy a file into target directory, there will a temporary `._COPY_` file for a period of time. The duration depends on file size. If we do not skip this file, we will may read the same data for two times.

## How was this patch tested?
update unit test

Author: uncleGen <hustyugm@gmail.com>

Closes #16370 from uncleGen/SPARK-18960.