D16877: Cleanup windowInterface in tests before windowManagement is destroyed

[David Edmundson]

davidedmundson added a subscriber: mart.

REPOSITORY
  R127 KWayland

REVISION DETAIL
  https://phabricator.kde.org/D16877

To: davidedmundson, #kwin
Cc: mart, kde-frameworks-devel, michaelh, ngraham, bruns