[DevOps Adoption] Rolling month view of devops adoption table
Problem to solve
Since #289856 (closed), the DevOps Adoption table has displayed data for the current calendar month. (Originally it displayed data for the previous calendar month.) There is a problem with this: if I view the table on the 1st of the month it is possible that none of the features have been used yet in the current month, so adoption will be zero. This could give the wrong impression that my teams are not using GitLab.
Proposal
For both the instance-level and group-level features, the DevOps Adoption table should show data for the previous 30 days. This resolves the problem with the "current calendar month" approach (zero adoption at the beginning of the month), without re-creating the problem with the "previous calendar month" approach (data being too stale). Note that we should continue processing and storing calendar month data for the sake of the upcoming adoption over time chart.