How to detect the current report in settings.twig
At the time of this post, the only variable available to the settings template that might help you out is the settings object: {{ dump(settings) }}.
As this is the Twig Template report, you might be able to use the settings.resultsTemplate value to identify the active report in a shared settings file.

I've opened a ticket for adding improved support for this scenario and will look into making the dataSource object available to the settings template in a coming release.