We recently moved from the "old" antithesis infra to the "new" antithesis infra. The repl set config on the "old" antithesis infra would use some setting to force more rollbacks and trigger more failures in antithesis. Typically there would be > 2000 rollbacks per run and we would find a handful of bugs. With the new infra, we are seeing 0 rollbacks and have not been finding many bugs.

We need to add the setting from the "old" infra to the "new" infra: https://github.com/mongodb/mongo/blob/bcf8d9b642c0be9b02fa27d85a77417291867ae6/buildscripts/antithesis/topologies/sharded_cluster/scripts/mongos_init.py#L17-L20