Bug 25238: Fix semantic heading for opac-details

Bug 25238: Fix semantic heading for opac-details

Prior to this patch the opac-details view contained multiple h1 level
headings.

Test plan
1/ Perform a search in the OPAC that will yield results
2/ Navigate to any results detailed view
3/ Inspect the page and note that two H1 level headings are present
(Page title + Item title)
4/ Apply the patch
5/ Reload the page
6/ Inspect the page and ntoe that the 'Item title' is now a level 2
heading
7/ Note the page still appears nicely
8/ Signoff

Bonus points: Check with XSLT views enabled and disabled, MARC21,
UNIMARC and NORMARC variations.

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>
(cherry picked from commit 3e18402c240814d7f00a62c3f2359bd9b9d0a098)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 0e711e024e2ac25347a17d6499289d90c6da29de)

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>

(cherry picked from commit 7519f4d065d258653a08cf46a8b142e702ca5af0)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>