LU-8865 tests: add fs_test test

LU-8865 tests: add fs_test test

Patch adds parallel-scale fs_test test.

Formerly it is MPI-IO test and it provides I/O performance
results for Effective bandwidths. We used fs_test to generate
a maximum IO write and read bandwidth scenario where a lot of
data is written to amortize away the overhead of open/sync/close
operations.

Test-Parameters: trivial testlist=parallel-scale
Seagate-bug-id: MRP-3914
Signed-off-by: Chennaiah Palla <chennaiah.palla@seagate.com>
Change-Id: I6057c8269fa72a151a792dcf1d05d30f4882204d
Reviewed-on: https://review.whamcloud.com/23932
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Elena Gryaznova <elena.gryaznova@seagate.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>