Bug 12264: Correct tiny typo in t/db_dependent/Items.t

Bug 12264: Correct tiny typo in t/db_dependent/Items.t

One of the tests claims 'item-level_itypes is disabled'
when it should be 'item-level_itypes is enabled'.

Patch fixes this.

To test:
- run t/db_dependent/Items.t
- tests should all pass
- verify the last test reads 'enabled'
- look at the code and see it's true

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>