Rolling 28 day time period for all usage ping counters
Problem
As a part of the work to enhancing usage ping to capture SMAU, counters were enhanced to count unique users over a rolling 28 day period for the counts in usage_activity_by_stage.
With the north star metrics project and increasing usage (after the performance optimizations) of Usage Ping data, its difficult to use the all-time counters for monthly metric reporting (its possible to take the number for this Month, and subtract it from Month - 1 and assume the difference is the metric for this month - not very accurate)
Proposal
Add a rolling 28-day time period for all counters