Skipped tests can't set up testMetadata types

QUnit assign skipped tests callbacks to be an empty function so that the tests are completely ignored.(https://github.com/qunitjs/qunit/blob/5bea87b0f2974b49e8bf907aa2b197ee469fe99b/src/test.js#L83)

As all hooked functions (e.g. `setupApplicationContext`, `setupRenderingContext`) are not invoked skipped tests don't set up types and end up neither application nor rendering tests.