Bug 28829: Remove single quote escaping in value_builder/unimarc_field_4XX.pl

Bug 28829: Remove single quote escaping in value_builder/unimarc_field_4XX.pl

Since Bug 23777 added To.json, single quote escaping in value_builder/unimarc_field_4XX.pl is useless.

Test plan:
1) Use UNIMARC database
2) Define value builder unimarc_field_4XX on 463$t
3) Create a record B1 with 200$a : L'avion
4) Create a record B2
5) Click on value builder in 463$t
6) Search for record B1
7) Click on "Choose"
=> Without patch 463$t contains : L\'avion
=> With patch 463$t contains : L'avion

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>