xfstest: enable xfs_repair for large filesystem testing

xfstest: enable xfs_repair for large filesystem testing

Now that large filesystem testing does not play free space games to
fill the space without IO, we can enable xfs_repair when running in
this mode. xfs_repair has had it's scalability problems solved, too,
so this is a safe thing to do.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Rich Johnston <rjohnston@sgi.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>