Summary
The feature branch is "wt-8372-format-mirror-objects", and here's the PR: https://github.com/wiredtiger/wiredtiger/pull/7662/files# 

Acceptance Criteria (Definition of Done)
This ticket is to just understand the change: mirrored tables and tracing, and how it integrates into test format. In the scope of this ticket we need to compile and run the test. Also, we need to learn how to interpret test results, failures in particular.