Bug 10809: use branches template plugin in serials search

Bug 10809: use branches template plugin in serials search

In serials-search.pl, branch name was computed using branch code and
then passed to template.

This patch uses the new template plugin now for this:
    Koha::Template::Plugin::Branches.

Test plan :
- Go to serials search
- Perform a search that returns at least an open an a closed subscription having a branch defined
=> The branch name is displayed in "Library" column

Signed-off-by: Pierre Angot <tredok.pierre@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>