LU-13170 osd: positive lookup shouldn't return an error

LU-13170 osd: positive lookup shouldn't return an error

because of stale OI, otherwise LFSCK has no chance to
fix direntry. lookup should initiate OI scrubber and
give it a hint about FID->dnode mapping.

This should fix sanity-lfsck/23b failing with ZFS often.

Test-Parameters: fstype=zfs testlist=sanity-lfsck env=ONLY=23b,ONLY_REPEAT=200
Change-Id: Iea826de9995e34939eff2d67a831deb6b192bd4d
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/37322
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>