Bug 25375: Match current Zebra availability limit

Bug 25375: Match current Zebra availability limit

In Zebra the availability limit code states:
'available' is defined as (items.onloan is NULL) and (items.itemlost = 0)

We should make ES follow the same behaviour so that changing the engine does not
change this.

To test:
1 - Find or create several records with two items each
2 - For those records setup items as:
    a - one checked out, one available
    b - both marked lost
    c - both damaged
    d - both withdrawn
    e - both notforloan
3 - Enable ES and reindex to confirm everything is set
4 - Perform an advanced search to return those records and 'limit to available items'
5 - Confirm you see records b,c,d,e and records say '2 items, none available'
6 - Apply patch
7 - Run `misc/search_tools/rebuild_elasticsearch.pl -d -b`
8 - Perform an advanced search to return those records and 'limit to available items'
9 - Confirm you see records a,b,c,d and al but a say '2 items, none available'

Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>