Disable AFTv5 feedback submission on dewiki

as per
https://de.wikipedia.org/wiki/Wikipedia:Meinungsbilder/Artikel-Feedback

this should be disable most (probably not all) ways for feedback
submission.

aftv5 itself should stay on for now.

Change-Id: I03409e3de3f27a77d6d21df8e5ff1b02ed66474e