Bug 32959: Don't store results of autobarcode in item editor templates

Bug 32959: Don't store results of autobarcode in item editor templates

Test Plan:
1) Enable autobarcode
2) Create a new item template, leave the barcode field blank
3) Apply that item template
4) Note the template prefills the barcode field
5) Delete that item template
6) Apply this patch
7) Restart all the things!
8) Repeat steps 2-4
9) Note the barcode field remains empty!

Signed-off-by: Phil Ringnalda <phil@chetcolibrary.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>