Bug 25786: Holds Queue building may target the wrong item for item level requests...

Bug 25786: Holds Queue building may target the wrong item for item level requests that match holds queue priority

Bug 23934 removed the limitation that prevented item level holds from
getting local holds priority. The problem is the code has never checked
if the item level hold matches the given item! This means the wrong item
may be requested to fill an item level hold.

Test Plan:
1) Create 3 items on a record
2) Place a hold for the 2nd item you created
4) Ensure that hold would be picked up by local holds priority
5) Build the holds queue
6) Note the holds queue is asking for the wrong item!
7) Apply this patch
8) Rebuild the holds queue
9) Holds queue should now be asking for the correct item!

Signed-off-by: Kim Peine <kim@williston.lib.vt.us>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>