Bug 23411: Do not fall back to 'email' for SMS messages

To test:
 1 - Have a patron wiht an sms number, but no email
 2 - Enable sms by setting SMSDriver syspref to Email
 3 - Set Notice triggers to send an overdue via sms and email
 4 - Ensure the selected notice is defined only for 'email'
 5 - Checkout an overdue to the patron above
    You can set a specify a due date in the past
 6 - perl misc/cronjobs/overdue_notices.pl -t
 7 - Check the patron notices tab, they have a print notice and an SMS notice pending
 8 - The SMS notice used the 'email' template
 9 - Apply patch
10 - sudo koha-mysql kohadev
11 - DELETE * FROM message_queue WHERE borrowernumber={borrower as above};
12 - Run the cron again
13 - Patron should have a print notice queued, no sms
14 - Define an SMS notice
15 - delete the message queue
16 - Run again
17 - The patron should have a print and an SMS

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Joy Nelson <joy@bywatersolutions.com>
(cherry picked from commit 64d8beafa8)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

misc/cronjobs/overdue_notices.pl

@@ -699,8 +699,8 @@ END_SQL
                                                 'count'         => $itemcount,
                                                },
                             # If there is no template defined for the requested letter
-                            # Fallback on email
-                            message_transport_type => $letter_exists ? $effective_mtt : 'email',
+                            # Fallback on the original type
+                            message_transport_type => $letter_exists ? $effective_mtt : $mtt,
                         }
                     );
                     unless ($letter) {