Bug 26992: Fix serial issue and related items deletion on serial collection page

Bug 26992: Fix serial issue and related items deletion on serial collection page

serial-collection.pl uses C4::Items::DelItemCheck() function which is obsolete.

Test plan:

1. Create a subscription with items created when receiving.
2. Receive several issues, and create corresponding items.
3. On Serial collection page (serial-collection.pl), select several issues.
4. Click on button Delete selected issues
5. A confirmation page is displayed. Enable "Delete associated items?".
   Then click on "Yes, delete" button.

   You get this error: Undefined subroutine &C4::Items::DelItemCheck

6. Apply the patch an repeat steps 3-5.
   Check that issues and related items are deleted.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>