Bug 33206: Bad title__sort made of multifield 245

Bug 33206: Bad title__sort made of multifield 245

In MARC 21, having title search field defined in mappings.yaml as 245abp
(more than one subfield), the Koha generated title__sort will have not
only $a, but also other subfields cut by ind2 characters, i.e.:

245 04 $a Die Renaissance : $b Architektur, Plastik, Malerei, Illustrationen, Zeichnungen

becomes as title__sort:

Renaissance : itektur, Plastik, Malerei, Illustrationen, Zeichnungen

instead of:

Renaissance : Architektur, Plastik, Malerei, Illustrationen, Zeichnungen

This is because copying an array of pointers in Perl causes you to
point to the same (anonymous) element.  Therefore, the intended
modification only for subfield "a"
(Koha/SearchEngine/Elasticsearch.pm, ~line 1157) causes in fact
modification for all the subfields sharing the same mapping
definition and introduction of the nonfiling_characters_indicator to
all subfields 245 when processing 245abp.  And this is obviously not
what is intended and results (in some cases) with bad sort order
when sorting by titles.

Test plan
=========
1. Have a standard Koha ES installation. In mappings.yaml
   you should have 245abp for title search field.

2. Insert / download / modify a record with 245 $b or $p,
    an article at the beginning of the title, and correctly
    set 2nd indicator. For instance:

245 04 $a Die Renaissance : $b Architektur, Plastik, Malerei, Illustrationen, Zeichnungen

3. In ES, with Kibana or culr, control the content of
   title__sort field for the related document.  It will be:

Renaissance : itektur, Plastik, Malerei, Illustrationen, Zeichnungen

4. Apply the patch, full reindex ES (--rebuild -r -d -a -b)

5. In ES, with Kibana or culr, control the content of
   title__sort field for the related document.  It should
   be now correct, i.e.:

Renaissance : Architektur, Plastik, Malerei, Illustrationen, Zeichnungen

Signed-off-by: Nick <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>