[effects/wobblywindows] Remove traits of an open/close animation

Summary:
Wobbly Windows effect is capable of animating a window when it's shown
or hidden. However, this feature has been hidden since it was added.
One needs to know how the effect works in order to enable these animations.

Therefore there's no good reason to keep these two animations because
practically no one uses them and they only add maintenance burden.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D23763