Traffic absent alerts causing pager noise

Summary

We're getting a lot of pages for sparse metrics (metrics that are intermittently reported). When they go missing, we get alerted because traffic seems to be "absent" - but there was never any traffic in the first place.

I suspect it has something to do with how we're using offset 1h or unless on our alerting rules.

Related Incident(s)

• production#8520
• production#8507

Desired Outcome/Acceptance Criteria

We are no longer getting *TrafficAbsent alerts for things that had no traffic to begin with.

Associated Services

Corrective Action Issue Checklist

• Link the incident(s) this corrective action arose out of
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