Disable kasp test on Windows

The kasp system test is timing critical. The test passes on all Linux based machines, but fails frequently on Windows. The test takes a lot more time on Windows and at the final checks fail because the expected next key event is too far off. For example:

I:kasp:check next key event for zone step2.algorithm-roll.kasp (570) I:kasp:error: bad next key event time 20909 for zone
step2.algorithm-roll.kasp (expect 21600) I:kasp:failed

This is because the kasp system test calculates the time when the next key event should occur based on the policy. This assumes that named is able to do key management within a minute. But starting, named, doing key management for other zones, and reconfiguring takes much more time on Windows and thus the next key event on Windows is much shorter than anticipated.

That this happens is a good thing because this means that the correct next key event is used, but is not so nice for testing, as it is hard to determine how much time named needed before finishing the current key event.

Disable the kasp test on Windows now because it is blocking the release. We know the cause of these test failures, and it is clear that this is a fault in the test, not the code. Therefore we feel comfortable disabling the test right now and work on a fix while unblocking the release.