Bug 15838 - Subscription duplicating: Reset fields from SubscriptionDuplicateDroppedI...

Bug 15838 - Subscription duplicating: Reset fields from SubscriptionDuplicateDroppedInput syspef by getting them using name instead of id

How I tested:
Verified bug with start and end date (were not cleared without patch).
After applying the patch all fields defined in SubscriptionDuplicateDroppedInput
were cleared as expected.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com
(cherry picked from commit 873a49f13b79bf1f5f7163f217cfc3a317ce602f)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>