chore: use status event instead of checks

Created by: bobheadxi

Looks like buildkite doesnt show up in checks, but I'm pretty sure they they show up in commit status. This change simplifies the run to just renovate whenever the main branch goes green. Another follow-up to #13449

Can't filter on just buildkite status changes, because Actions be like that (https://docs.github.com/en/developers/webhooks-and-events/webhook-events-and-payloads#status)