Bug 34095: Adjust logic so that shipment cost is empty if the receiving shipment...

Bug 34095: Adjust logic so that shipment cost is empty if the receiving shipment cost is blank.

Signed-off-by: Anneli Österman <anneli.osterman@koha-suomi.fi>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit a5cadff4829eb62624ac839799b9b13c8cc7eac6)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit f5e151c1f8842f0900d6aa5855d623dd967392b2)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>