Bug 23995: Remove CHECK constraints from kohastructure

Bug 23995: Remove CHECK constraints from kohastructure

MySQL8 and MariaDB10.3 impliment check constraints but utilise
different, incompatible, syntaxes to do so.

This patch removes the check constraints entirely whilst we work on a
better solution to work around the incompatabilities of the two DBs.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 0d2cc574d1c8ac00cebd91816277c75a461eef3b)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>