Don't mention "firewall" in Tails Greeter anymore

Back in the day, there use to be a configuration option in Tor Launcher for strict firewall allowing only port 80 and 443 but it’s not the case anymore. As of today, Tor Launcher is not mentioning the word “firewall” anywhere. So let’s drop this. It’s a complex word that can mean many different things (“Is this about configuring my firewall?”) and doesn’t relate to anything in Tor Launcher down the road.

Feature Branch: feature/12382-dont-mention-firewall

Parent Task: #8230 (closed)

Original created by @sajolida on 12382 (Redmine)