Bug 31887: Fix search on MARC field in Elasticsearch mappings table

Bug 31887: Fix search on MARC field in Elasticsearch mappings table

In Elasticsearch mappings table, in tabs with MARC fields, searching using DataTable search field does not work for MARC fields / subfields.
This is because cell contains an input HTML tag with MARC data in attribute value.

Test plan :
1) Go to Administration > Search engine configuration (Elasticsearch)
2) Go to tab 'Bibliographic records'
3) Enter in search field a used MARC field (like 245)
=> Table gets filtered by rows with mapping on searched field
4) Enter in search field the field+subfield used for issues (952l in KTD)
=> Table gets filtered by rows with mapping on field+subfield

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>