Bug 26583: Remove unneccessary code in AddIssue

Bug 26583: Remove unneccessary code in AddIssue

The lines to calc due date are doubled

ModDateLastSeen is not needed as we set the item not lost and we can set
the date as we do for date last borrowed and save a DB store

Largely this is reading the code and confirming the changes make sense

To test:
1 - Apply patch
2 - Check out items, confirm it works as before
3 - prove -v t/db_dependent/Circulation.t

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>