[core] Alerting when services go down

[AquiGorka]

Figure out what would be the best way for us to learn when the solver, job creator and/or chain services stop working for whatever reason.

[bgins]

We have started this effort with:

• [x] EC2 status checks
• [x] Cloudflare tunnel alerts when tunnel goes down

Next steps:

• [ ] Implement Cloudflare tunnel alerts in OpenTofu
• [ ] Add a periodic cowsay job to check network liveness
• [ ] Alerts from our observability stack once live