Hide tooltip when PrivateActionToolButton is pressed

Summary: The tooltip used to remain even as the button was pressed, now it doesn't/shouldn't.

Test Plan: Look at a bunch of instances of this and make sure the tooltip hides on button press.

Reviewers: Plasma, Kirigami, ngraham, mart

Reviewed By: Kirigami, ngraham

Subscribers: ngraham, mart, plasma-devel

Tags: Kirigami

Differential Revision: https://phabricator.kde.org/D21877