[SPARK-4619][Storage]delete redundant time suffix

Time suffix exists in Utils.getUsedTimeMs(startTime), no need to append again, delete that

Author: maji2014 <maji3@asiainfo.com>

Closes #3475 from maji2014/SPARK-4619 and squashes the following commits:

df0da4e [maji2014] delete redundant time suffix

(cherry picked from commit ceb628197099e6c598cde1564ed9c1c3681ea955)
Signed-off-by: Reynold Xin <rxin@databricks.com>