LU-16623 tests: ignore sanity-pfl stripe-count off-by-1

LU-16623 tests: ignore sanity-pfl stripe-count off-by-1

In some cases the MDS may not create all stripes on a file, if the
MDT-OST connection does not have precreated objects.  This is OK,
so the tests should not fail the stripe-count check if trying to
create a fully-striped file and one of the stripes is missing.

Lustre-change: https://review.whamcloud.com/54778
Lustre-commit: TBD (from 6380f3f13f7ffe854365bf55410bb34db801529a)

Test-Parameters: trivial testlist=sanity-flr
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ie482fdf86f82e7a2292c021761885249a6c551f1
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54779
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>