Bug 16847: Remove C4::Members::GetTitles

Bug 16847: Remove C4::Members::GetTitles

This subroutine just reads the content of a pref, split it, add an
empty string and returns.
It is not really useful and the code in the script (memberentry.pl) uses
the only occurrence of CGI::popup_menu
Let's remove it and build the dropdown list in the template.

Test plan:
1/ Empty BorrowersTitles, edit a patron and confirm that the "Salutation"
does not appear
2/ Fill BorrowersTitles with "Mr|Mrs|Miss|Ms", edit a patron and confirm
that the "Salutation" dropdown list is correctly filled.
The default option should be selected if you are editing a patron with a
title defined.
This should also be tested at the OPAC.

Followed test pan, works as expected in Staff and OPAC
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 131002e6230f2b69f0d6007b75fbc90444745b68)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>