Bug 35695: Remove useless JS from cataloging_additem.js

Bug 35695: Remove useless JS from cataloging_additem.js

To test:
1. APPLY PATCH
2. Turn on EnableItemGroups
3. Go to a record with item groups, or create some.
4. Add an item, making sure items can be added to a group. ( Bug 33639 must be applied )

If I am wrong and this code should stay, tell me. I'll fix the jQuery instead of removing it. :)

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit cbc97f5c685e4e97f2d5f5c834f489869d5e2e4c)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>