EX-8041 utils: lpurge to use 2nd-stripe objects

EX-8041 utils: lpurge to use 2nd-stripe objects

in some cases lpurge must be considering objects which are not
first stripe (another lpurge can be waiting for thresholds, etc).

Test-Parameters: mdscount=2 mdtcount=4 trivial testlist=hot-pools

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Iccc0b6af6f283287b41d6f16c875c56f83413e2e
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51884
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>