Bug 14142 - Holds queue viewer only displays first subtitle from marc keyword mappings

Bug 14142 - Holds queue viewer only displays first subtitle from marc keyword mappings

Despite the point of the Keyword to MARC Mappings being to simplify the
handling and display of repeated values from multiple subfields, the
holds queue viewer will only display the first value found. What it
should be doing instead is displaying all fields that match the subtitle
keyword.

Test Plan:
1) Apply this patch
2) Define multiple Keyword to MARC mappings for the subtitle keyword
3) Place a hold on a record using those subtitle fields
4) View the hold in the holds queue viewer
5) Note that all the subtitles now appear

Signed-off-by:Heather Braum <hbraum@nekls.org>

Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
(cherry picked from commit d76c9f4850c9ba7605f2c405838f973c70a70b61)
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>