Bug 25756: remove erroneous hyphen

Bug 25756: remove erroneous hyphen

In the Staff Client, the OPAC "Appearance" preferences table has an
extra, empty HTML table row at the end.

Test plan:
0) Observe the empty HTML table row at the end of the table that lists
   OPAC "Appearance" system preferences.
1) Apply this patch.
2) Observe that the empty table row is now gone.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>