Prefix screenshot and video of tests with the configuration name for unicity

There's currently a limitation in Jenkins when archiving artifacts: they are copied without caring about their locations. And since we run the same test several times but with different configurations, the test name is not enough to uniquely point to a given test in a given configuration. Thus we also need to save the configuration name, even though the directory in which we're saving the screenshot is already named after the executing configuration name.