[6.x] allow adding NotFoundHttpException to "allowed" exceptions in tests

[kbond]

Currently, it is not possible to have:

/**
 * @test
 */
public function my_test()
{
    $this->handleExceptions([
        NotFoundHttpException::class,
    ]);

    // ...
}

This is because the checking for NotFoundHttpException happens before checking the "excepts" in InteractsWithExceptionHandling. This PR ensures checking for "excepts" happens first.