LU-18086 obdclass: do not use seeks to store pool order

LU-18086 obdclass: do not use seeks to store pool order

Seeks field is used to decide how many elements to free
at shrink. Changing it leads to wrong shrink strategy and
finally to the OOM.

Let's use another means to store pool order.

Test-Parameters: trivial testlist=sanity-compr
Test-Parameters: trivial testlist=sanity-compr
Fixes: 93af01f966 ("LU-16724 ptlrc: ptlrpc: extend sec bulk functionality")
Change-Id: I075d6d139aedea29df03bafae1fac592e671656b
Signed-off-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Signed-off-by: Sergey Cheremencev <scherementsev@ddn.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55913
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>