Bug 29427: Make SMTP transport set debug mode correctly

Bug 29427: Make SMTP transport set debug mode correctly

This patch makes the _transport_ method in Koha::SMTP::Server pass the
debug flag correctly to the Email::Sender::Transport::SMTP->new
constructor.

To test:
1. Apply the regression tests patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/SMTP/Server.t
=> FAIL: Oh noes! debug is not passed to the constructor!
3. Apply this patch
4. Repeat 2
=> SUCCESS: Hey! It is being set!
5. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>