LU-8777 mdt: add parameter to disable remote/striped dir

LU-8777 mdt: add parameter to disable remote/striped dir

Restore mdt_enable_remote_dir to enable/disable remote directory
feature, and also add mdt_enable_striped_dir and
mdt_enable_dir_migration for striped directory and directory
migration.

Enable remote directory, striped directory and directory migration
by default.

Add sanity.sh 417.

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: I583dbc5a5eb54de02c8a4459092d4a3f3b24b262
Reviewed-on: https://review.whamcloud.com/24498
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>