LU-5490 tests: Sanity/133d ensure stats read is on correct MDT

LU-5490 tests: Sanity/133d ensure stats read is on correct MDT

Ensure directories used to collect rename_stats are on the MDT
that is checked.  This ensures directories are created on
MDT0 and not striped and then rename_stats is read from MDT0.

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: Ib27f5c531f2d8bd664ec3a4732c512b0c389dc43
Reviewed-on: https://review.whamcloud.com/31585
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>