LU-16032 tests: restore delay_unlink_mb in sanity/360

LU-16032 tests: restore delay_unlink_mb in sanity/360

Restore the original value of osd-ldiskfs.*.delay_unlink_mb after
sanity test_360 is finished, so that it doesn't have an impact on
later tests running, in particular sanity-quota.sh was seeing some
delay in freeing quota for files that were just deleted.

Lustre-change: https://review.whamcloud.com/53218
Lustre-commit: TBD (from 8fa0580fd64fe7cbe969817ece87a161c517c4c3)

Test-Parameters: trivial testlist=sanity-quota
Fixes: a772e90243 ("LU-16032 osd: move unlink of large objects to separate thread")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I7c1ab02262afdef2fc51f9fbc3932d954a4f8304
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53219
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>