LU-13693 lfs: check early for MDS_OPEN_DIRECTORY

LU-13693 lfs: check early for MDS_OPEN_DIRECTORY

In mdt_reint_open() check earlier for MDS_OPEN_DIRECTORY/O_DIRECTORY
to avoid breaking leases used by lfs mirror when calling lfs
getstripe. Add a multi client version of sanity test_210 to sanityn.

Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: I1860fc76c8014da3e637d83b487cb28b037ba71b
Reviewed-on: https://review.whamcloud.com/39159
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>