diagnostics: no false positive errors

During the hackathon, while discussing with a FreedomBox user who did not have much experience with GNU/Linux or servers, I learned that the way a beginner user responds to failing diagnostics is very different compared to expert users.

If an expert user sees a diagnostic failure, they will check if the app's functionality is working as expected, and then they can ignore the failure and continue using the app.

But for a beginner, they may think that they cannot use the app until the failing diagnostic is fixed.

When a FreedomBox and its apps are running as expected, there should not be any diagnostic failures. The diagnostics that cause false positives should be either fixed or removed.

This is a generic issue that can point to other specific issues.

Current failures:

• networks: Using DNSSEC on IPv4 / IPv6 (#1607 (closed))
  • Depends on ISP?
• tor: Access URL http://www.debian.org on tcp6 via Tor / Confirm Tor usage at https://check.torproject.org on tcp6
  • IPv6 may be deactivated?
• bind: Port dns (53/tcp, 53/udp) unavailable for external networks
  • Seen on stable only.
  • Doesn't seem to be due to bind module. Maybe something else added the port to external zone?
• privoxy: IPv6 issue (https://discuss.freedombox.org/t/issues-with-ipv6-privoxy-and-tor-proxy-after-updating-to-freedombox-23-20/2798/1)