LU-6114 test: add $mbench_OPTIONS to run_metabench()

LU-6114 test: add $mbench_OPTIONS to run_metabench()

Cray's metabench version requires -p <dictionary> parameter.
Patch adds mbench_OPTIONS to metabench call.

Signed-off-by: Elena Gryaznova <elena.gryaznova@seagate.com>
Xyratex-bug-id: MRP-1113
Reviewed-by: Vladimir Saveliev <vladimir_saveliev@xyratex.com>
Reviewed-by: Alexander Lezhoev <Alexander_Lezhoev@xyratex.com>
Change-Id: Id00f96c034f3d2d501421c0dd435354becea7512
Reviewed-on: http://review.whamcloud.com/13388
Tested-by: Jenkins
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>