Add compatibility test for setDefaultRWConcern

[eerxuan]

Part of #42.

Category: system / administration / commands

Add compatibility test coverage for the setDefaultRWConcern feature.

Note: a smoke test exists; comprehensive compatibility test coverage is needed.

[vic-tsang]

/take

[github-actions]

Assigned to @vic-tsang!

[documentdb-triage-tool]

👋 @vic-tsang — this issue has been assigned for 26 days with no activity. Is it still in progress? If you've made progress, please leave a quick update. Otherwise it'll be flagged for re-assignment at the next triage meeting.

[eerxuan]

Comprehensive compatibility tests now exist on main (beyond the smoke test); closing.