[libkwineffects] Drop AniData constructor that receives QString
Summary:
This code has several bugs, it's untested, it's not used anywhere, it
adds unnecessary complexity -> delete it.
Test Plan: Compiles.
Reviewers: KWin, davidedmundson
Reviewed By: KWin, davidedmundson
Subscribers: kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D16099