Bug 23049: (follow-up) Remove duplicate of mandatory data

Bug 23049: (follow-up) Remove duplicate of mandatory data

This patchset originally introduced the manadatory data into
/en/mandatory/account_debit_types.sql. However, it was later decided to
maintain the system types description strings in the templates and as
such the database data file was moved to the top level.  This patch
removes the now superflous /en/mandatory version.

Once we have the sql files easily translated via the standard
translate.koha-community.org toolchain we should restore this approach
and update the templates to use the descriptions from the database.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>