Bug 32302: (follow-up) Hide ISBN label when list sent from the staff interface

Bug 32302: (follow-up) Hide ISBN label when list sent from the staff interface

This makes the same change to the staff interface. Lists sent
from the staff interface hide the ISBN label in the email message
when there are no ISBNs for a record.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 69ddb83f41cfc5c9eb6b4e483bca9316bac98db8)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>