Bug 18037: Hold notes template cleanup (from 15545)

Bug 18037: Hold notes template cleanup (from 15545)

From the second patch of bug 15545:
Removing some unused template code related to a former approach.
Adding some changes for future extension by bug 15545.

This patch was tested by Liz Rea when the routine IsHoldNoteRequired was
called by opac-reserve.pl. The only change here is that we do not yet
call this routine; so leaving her original signoff.

Test plan:
[1] Enable OPACHoldNotes.
[2] Place a hold on a serial record. No behavior change.

Signed-off-by: Liz Rea  <liz@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>