QEventLoop: Remove the test that checked throwing from an event handler

In Qt 5, we declared that throwing from event handlers is undefined
behavior. So stop testing this.

We will try our best to capture and pass along std::bad_alloc, but even
that might not work, depending on compiler settings. In particular,
after the upgrade to MinGW/GCC 4.8 with DW2, this test stopped working.

Task-number: QTBUG-31615
Change-Id: Ibf5fb2ce0c48b983549096bf7aac434b6ed3ac2e
Reviewed-by: Lars Knoll <lars.knoll@digia.com>