misc: drop the dangerous label from xfs_scrub fsstress tests

misc: drop the dangerous label from xfs_scrub fsstress tests

Now that online fsck has been in the upstream kernel for 8 months, I
think it's stabilized enough that we don't need to hide the stress tests
behind the "dangerous" label anymore.

Also rename fsstress_repair to fsstress_online_repair to be consistent
with the online_repair group.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zorro Lang <zlang@kernel.org>