LU-10786 tests: add stripe size to lfs setstripe

LU-10786 tests: add stripe size to lfs setstripe

Since the default stripe size increased from one to four
MB, we need to add the stripe size parameter to calls
to 'lfs setstripe' for composite files when the component
size is less than the file system stripe size. Thus, add
the stripe size parameter to calls to 'lfs setstripe' for
sanity-flr tests 45 and 46 and sanity-pfl test 16.

Test-Parameters: trivial testlist=sanity-flr,sanity-pfl

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: Ic169eaebd922175467f010b159a2b065fb91b3fb
Reviewed-on: https://review.whamcloud.com/31569
Reviewed-by: Jian Yu <jian.yu@intel.com>
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>