LU-9345 tests: use hsm_remove with --mntpath for deleted files

LU-9345 tests: use hsm_remove with --mntpath for deleted files

In test_29d of sanity-hsm, to run "lfs hsm_remove" on a file deleted
from Lustre, one has to use the --mntpath option.

Test-Parameters: trivial testlist=sanity-hsm clientcount=3 envdefinitions="ONLY=29d"
Signed-off-by: Quentin Bouget <quentin.bouget@cea.fr>
Change-Id: I35865c059e498e1a0ced0cebeac22a8491231e00
Reviewed-on: https://review.whamcloud.com/27006
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>