The Per Period Metrics feature was added back in 15.9.2 for GCP customers, but not seeing the Time Slicing Group by job in 15.9.2.
Release : 15.9.2
Component : CA PPM SAAS TIME SLICING
The job was renamed from Time Slicing Group By in 15.9.1 to Time Slicing Sync in 15.9.2.
See the below reference to this change from the 15.9.2 Release Notes at: Time Slicing Group By Job Renamed to Time Slicing Sync
Time Slicing Group By Job Renamed to Time Slicing Sync
Time Slicing Group By Job has been renamed to Time Slicing Sync in this release. The job and the associated SQL Curve per-period metrics are now available for Clarity SaaS customers. To learn more about this job, see Clarity Jobs Reference.
See Clarity Release Notes (Release notes for Clarity 15.9.2)