LU-1233 tests: clean up files in performance-sanity test

LU-1233 tests: clean up files in performance-sanity test

This patch cleans up the files created in performance-sanity.sh
through mdsrate-{create,lookup,stat}-*.sh after create/lookup/stat
operation fails.

Test-Parameters: envdefinitions=SLOW=yes,ENABLE_QUOTA=yes \
testlist=performance-sanity

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: Ied70b273aa036389d28416c33d6f4e56ba5697a4
Reviewed-on: http://review.whamcloud.com/8265
Tested-by: Jenkins
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>