Bug 16742: Remove unused template subject.tt

Bug 16742: Remove unused template subject.tt

The template koha-tmpl/intranet-tmpl/prog/en/modules/catalogue/subject.tt
is not used and can be removed.

To test:
- Apply patch
- Verify that catalogue/moredetail.pl works as before (go to a
  biblio with items and click 'Items' in left hand menu)

Signed-off-by: Hector Castro <hector.hecaxmmx@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>