feat(cron): Custom checkInId

[danilofuchs]

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Fixes #9648

Important: I'm not sure this use case is supported by the Sentry API, and also it would make @sentry/node inconsistent with other SDKs.

Motivation is in #9648

[lforst]

I'd like to hold off here until we settled #9648 (comment). Thank you very much for the contribution in the meanwhile!