disable kcrashtest and its helper executable test_crasher on windows

Summary:
test_crasher gets stuck in a loop breaking the CI system. let's disable
the entire test until someone finds the interest to investigate a fix

Test Plan: still builds and runs on linux

Reviewers: apol

Reviewed By: apol

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D25153