Bug 18706 - subfields to delete not disabled anymore in batch item modification

Bug 18706 - subfields to delete not disabled anymore in batch item modification

In Tools > Batch item modification, one can click a checkbox to delete a subfield.
This click use to disable the input to change the field value.

This comes from the patch : Bug 13501: Move "Required" and checkbox after input/select
Because input is found using JQuery next().

This patch replaces with $(this).parent().find("[name='field_value']").

Test plan :
- Go to Tools > Batch item modification
- Enter a barcode and submit
- Click on a checkbox on a non-mandatory subfield
=> Without patch the input or select is not disabled
=> With patch the input or select is disabled
- Submit
=> Check that subfield is deleted

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>