Bug 30194: (follow-up) Remove invalid tests

Bug 30194: (follow-up) Remove invalid tests

This patch removes tests for the wrong 'Accept' header situation. It is
the only thing I found I could do.

The situation is: the JSON::Validator + Mojolicious::Plugin::OpenAPI is
trapping this case and returning its own error code (400) and it also
builds its own message! So no point testing it, as it can change again.

I post it as a separate patch just in case someone finds a better way to
handle this and obsoletes the patch :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Mason James <mtj@kohaaloha.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>