Updating Sentry downtime checks

[flakey5]

Enter your suggestions in details:

Opening this for tracking purposes;

re #7047 we didn't get a downtime alert in Sentry for the website project. We did however get one for the release worker, nodejs/release-cloudflare-worker#140, but it was tracking the status for nodejs.org and not the routes it serves.

Ideally we can change this so that,

1. the website project is checking for downtime of the website
2. the worker is checking for downtime of the routes it serves (currently r2.nodejs.org and nodejs.org/metrics)

[flakey5]

Hmm, so looking at the Sentry docs and I'm not sure if we are able to configure this yet? https://docs.sentry.io/product/alerts/uptime-monitoring/