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.

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