Bug 29067: Remove duplicate conditional statement from OPAC messaging settings title

Bug 29067: Remove duplicate conditional statement from OPAC messaging settings title

We can never reach the first [% ELSE %]Koha online[% END %] block in OPAC
messaging preferences title, so it's dead code.

This patch removes the useless duplicate if-statement.

To test:
1. Enable EnhancedMessagingPreferencesOPAC system preference
2. Go to /cgi-bin/koha/opac-messaging.pl
3. Observe title Your messaging settings > Koha online catalog
4. Apply patch
5. Refresh page /cgi-bin/koha/opac-messaging.pl
6. Observe same title Your messaging settings > Koha online catalog
7. See patch content
8. Confirm there are no functional changes in the new logic

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>