Flaky-crashing tests are invisible

As evidenced by the proceedings of https://codereview.qt-project.org/c/qt/qtdeclarative/+/648708 it's currently impossible to notice tests that crash unless they crash twice in a row or someone happens to look at the logs in great detail. That's horrible! A crashing test is worse than a failing test. It needs to be highlighted in bright red and the CI should repeatedly poke the maintainer in whatever way possible to fix it.