Bug 26762: Modify template logic in opac-reserves.tt to avoid error

Bug 26762: Modify template logic in opac-reserves.tt to avoid error

This patch makes a change to the OPAC hold template to prevent certain
cases where the output is invalid.

To reproduce, perform a search in the OPAC which will return some titles
which can be placed on hold and some which cannot.

 - Select all results (some holdable, some not)
 - Click the "Place hold" link
 - On the "Confirm holds" page the layout will be broken after the
   first instance of the message "There are no items that can be placed
   on hold."

To test, apply the patch and repeat the process above. After the patch
has been applied the "confirm holds" page should look correct.
Validating the HTML source should return no errors.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>