Fix going to prev/next article with keyboard when using load full website

Summary:
Articles were loaded three times when keyboard selection was used. This broke rendering so the selected article was never rendered.
This is a regression as keyboard selection was working one or two releases ago.

Test Plan: Set feed to use rendering of full website. Press left/right arrow. See different article displayed.

Reviewers: pinaraf

Reviewed By: pinaraf

Subscribers: dvratil, #kde_pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D12473