Additional commits pushed:
1. Adds a new function for purging user activity rows by activity type, leaving the most recent row per user, consistent with transience.
2. pgtap test for the above.
3. release notes.
Additional commits pushed:
1. Adds a new function for purging user activity rows by activity type, leaving the most recent row per user, consistent with transience.
2. pgtap test for the above.
3. release notes.