kill twitter support

Summary:
Twitter support in KAccounts has been reportedly broken for years (https://bugs.kde.org/show_bug.cgi?id=363260) and is currently disabled. Therefor the twitter plugin cannot work. We have no complaint about it not working in Purpose bugs, which makes me conclude it won't be missed.

It allows us to get rid of the ugly dependency on nodejs, too.

Reviewers: Frameworks, apol, bshah

Reviewed By: apol, bshah

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D27637