Bug 34823: Do not show Item group dropdown if there are no item groups

Bug 34823: Do not show Item group dropdown if there are no item groups

To test:
1. Enable EnableItemGroups and EnableItemGroupHolds
2. Go to the OPAC and log in as a patron
3. Go to any record that doesn't have grouped items and try to place a hold
4. Click on "Show more options"
5. See "Request specific item group:" and dropdown
6. APPLY PATCH
7. Try again, this time if the record has no item groups you should not see the dropdown at all.

Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Emily Lamancusa <emily.lamancusa@montgomerycountymd.gov>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>