LU-18558 scrub: don't release os_ls_fids too early

LU-18558 scrub: don't release os_ls_fids too early

a running iterator can use os_ls_fids (in osd_iit_iget()) even with
the scrubber thread completed which should not release os_ls_fids
too early.

Test-Parameters: testlist=sanity-scrub,sanity-lfsck
Test-Parameters: testlist=sanity-scrub,sanity-lfsck
Test-Parameters: testlist=sanity-scrub,sanity-lfsck
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I3c5739f3b475f368235344716cd1b596e7f11bd8
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57434
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>