Bug 19996: (RM follow-up) Remove commented use warnings;

Bug 19996: (RM follow-up) Remove commented use warnings;

These plugins are very noisy, badly written and I have no idea what they
do.
t/db_dependent/FrameworkPlugin.t outputs a log of warnings about "
uninitialized value".

Let fix them later.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>