Bug 27149: Don't strip itemnumber when adding item status via Z3950Responder

Bug 27149: Don't strip itemnumber when adding item status via Z3950Responder

This breaks MARCEdit integration as svc/bib uses the itemnumber field to update items

To test:
1 - sudo koha-z3950-responder --stop kohadev
2 - Run it manually:
    perl /kohadevbox/koha/misc/z3950_responder.pl -c /etc/koha/sites/kohadev/z3950 -u kohadev-koha -p /var/run/koha/kohadev/z3950-responder.pid -D -d kohadev-koha-z3950 -l /var/log/koha/kohadev/z3950.log
3 - Connect and search to verify itemnumber is in item records
    yaz-client localhost:2100
    base biblios
    find shuffle
    show 1+1
4 - sudo koha-z3950-responder --stop kohadev
5 - Run it manually to add item status
    perl /kohadevbox/koha/misc/z3950_responder.pl --add-item-status k -c /etc/koha/sites/kohadev/z3950 -u kohadev-koha -p /var/run/koha/kohadev/z3950-responder.pid -D -d kohadev-koha-z3950 -l /var/log/koha/kohadev/z3950.log
6 - Connect and search, no itemnumber in records
7 - Apply patch
8 - Stop, restart all the things, and manually start server with item status again
9 - Connect and search, itemnumbers are included

Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>