xfstests 050: ignore duplicates reported by repquota

xfstests 050: ignore duplicates reported by repquota

Arrange to ignore duplicate entries reported by the "repquota"
xfs_quota command.  This can happen if an id is used more than once
(such as when two user names are assigned the same uid).

Since we are already sorting the output we can accomplish this by
adding the "-u" (unique) option to the sort command.  Shorten some
long lines while we're at it.

Signed-off-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>