LU-9771 flr: inherit mirror options from directory

LU-9771 flr: inherit mirror options from directory

This patch checks and verifies directory inheritance from parent
works both for regular files and directories.

Test-Parameters: testlist=sanity-flr
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: Ief58805ca736acb9a53fd9ad8fb2bb460d46b748
Reviewed-on: https://review.whamcloud.com/29576
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>