People are not going to try. They have no way to know:

- that it's your IP and that you have permission from Hetzner to encourage people to attack it.

- that they would be immune to prosecution. That requires contracts with Hetzner.

Instead consider showing the results of your running of assorted load test against the IP, graphs, server stats, page response times based on packet rate, request rates, etc... and if applications are still responding, what techniques you used to keep them operational and accessible.