Enhance Uptime Monitoring to Handle Provider Blocking

We need to improve our uptime monitoring system to better handle situations where hosting providers block our IP addresses, leading to false downtime alerts. This issue covers the development of a solution that includes identifying blocking providers, modifying the monitoring status logic, and improving customer communication. ```[tasklist] ### Tasks - [ ] https://github.com/getsentry/sentry/issues/76874 - [ ] https://github.com/getsentry/sentry/issues/76875 - [ ] https://github.com/getsentry/sentry/issues/76877 - [ ] https://github.com/getsentry/sentry/issues/76878 ```