Bug 10452: make AllowHoldsOnDamagedItems control using damaged items to fulfill holds

AllowHoldsOnDamagedItems will stop item-specific holds from being placed
on damaged items, but does not stop Koha from using damaged items to
fill holds. This seems like incorrect behavior.

Test Plan:
1) Set 'AllowHoldsOnDamagedItems' to "Don't Allow"
2) Pick an item, set it to damaged
3) Place a bib-level hold on this item's record
4) Scan the item though the returns system
5) Koha will ask to use this item to fill the hold, click "ignore"
6) Apply this patch
7) Repeat step 4
8) Koha will not ask to use this item to fill the hold

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10452: [QA Followup] - Unit tests

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes all tests and QA script. Also checked
  t/db_dependent/Holds.t
  t/db_dependent/HoldsQueue.t

Tested holds triggering with different settings of
AllowHoldsOnDamagedItems. Works as described.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10452: (follow-up) remove duplicate check of damaged status

While reviewing the main patch for this bug to verify that the
holds queue routines and C4::Reserves had the same conception of
when a damaged item could fill a hold request, I noticed that
GetItemsAvailableToFillHoldRequestsForBib() duplicated the code
for adding an SQL clause to filter out damaged items.  This patch
removes the duplication and improves the POD for that routine.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>