Design what to do when automatic time sync before Tor in automatic mode fails

Blueprint: https://gitlab.tails.boum.org/tails/blueprints/-/wikis/robust_time_syncing/

What can/shall we do when #18717 (closed) fails?

On https://gitlab.tails.boum.org/tails/blueprints/-/wikis/robust_time_syncing#reasons-for-failure-of-the-automatic-time-sync we researched symptoms for such failures, and mapped them to possible causes.

Status quo: when this happens, we try to bootstrap Tor anyway.

Next steps are:

• Think about these scenarios: can we do better than try bootstrapping Tor anyway?
• If bootstrapping Tor fails too, then the exact failure mode we've hid when syncing time can be useful info to suggest troubleshooting steps.
  • Note: some improvements to our troubleshooting steps don't even need this new information; for example, if you're not using obfs4, we propose the user to fix their clock as the first item, but it's not very probable that is the reason.