The requirement is to not modify the `shardingtest.js` but to augment it. An example of how to do it is check_indexes_consistent_across_cluster.js that augments the `checkIndexesConsistentAcrossCluster`.

There is no goal to actually plug this hook to anything yet. We do not have any special shard startup flags for this project either, so the goal is to just override the constructor and prevent starting a separate config server, select which shard will be a config shard (make it shard 0 for now) and pretend to start this shard with a special flag (keep the flag variable empty because we don't have it).

Examine other examples where the `prototype.*=` pattern is used to learn all the known tricks in the toolbox and post relevant cases as comments here.