LU-8805 tests: fix defect introduced by LU-8226

LU-8805 tests: fix defect introduced by LU-8226

client loads run_tar.sh, run_dd.sh, etc. are
executed on remote nodes; ps -C does not select them
on main client.

Test-parameters: trivial testlist=recovery-mds-scale

Seagate-bug-id: MRP-4011
Signed-off-by: Elena Gryaznova <elena.gryaznova@seagate.com>
Change-Id: Iaa066298f96b14af148007410f29f5c7b965ee2c
Reviewed-on: http://review.whamcloud.com/23861
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>