Bug 24059: Remove unused Greybox assets from detail.tt

Bug 24059: Remove unused Greybox assets from detail.tt

This patch removes reference to the Greybox include file because it is
unused.

To test, apply the patch and view the bibliographic details page. Test
various JavaScript-driven interactions to make sure no functionality has
been broken: Menus, tabs, table filters, MARC Preview, etc.

Searching for "gb-" or "GB_" should return no results in any files
related to the details page.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>