Bug 17141: Call config method to retrieve logdir

Bug 17141: Call config method to retrieve logdir

Incorrect method call is causing runtime error and not
retrieving the correct logdir value
Change retrieves the value correctly

To test:
1) Run edi_cron.pl, notice error
2) Apply patch and run edi_cron.pl again, should work as expected

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Note: I did not test but changes make sense.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>