Bug 8338: Remove zero amount overdues on backdated returns where appropriate

Bug 8338: Remove zero amount overdues on backdated returns where appropriate

This patch removes any overdues which would be reversed on a backdated
return if CalcFineOnBackdate is enabled and the user has not already
attempted to pay off the accruing fine.

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 3f3534a8eeed87869fd6a858866455c10087d7e1)

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