Bug 16624: Fix regression displaying a letter with hours

Bug 16624: Fix regression displaying a letter with hours

Bug 13622 has introduced a bug, if pref TimeFormat is 12hr and a date is
displayed in both title and content of the letter.

Test plan:
1 - Checkout an item (with default time 11:59:00 PM)
2 - Generate a quickslip
3 - Notice the time is 'AM'
4 - Apply patch
5 - Generate quickslip
6 - Note time is correct

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 6f0ce92543319d243cf185e3df9f91a9cf7f6d87)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
(cherry picked from commit 917054eaf63e656a521dc5742e2124a186d7c96c)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>