The map_reduce* tests were disabled in transaction concurrency suites via the does_not_support_causal_consistency tag. However SERVER-95023 is removing that tag from being part of the exclude set in multi_stmt_txn concurrency suites.

This means that the map_reduce* tests will start running in the transaction concurrency suites. I ran a patch with them allowed, and things seemed fine – except for map_reduce_drop.js for which I filed SERVER-95150 – so it should be safe to run these tests. See comments for patch link.

Please double check and enable these tests in the concurrency suites. I've tagged them with a TODO on this ticket number and the tag does_not_support_transactions which is more appropriate.

Please wait until SERVER-95023 has gone in before starting this work.