Relevant slack thread: https://mongodb.slack.com/archives/CUHC9R8J0/p1629723535080100

mongosh code: https://github.com/mongodb-js/mongosh/blob/94ca4d917c6eb52e92bfaf708c7b5d4bb90ef4db/packages/shell-api/src/database.ts#L1328-L1385

legacy shell code: https://github.com/mongodb/mongo/blob/afdebef974ba087301976e32e36e78802cf89dc8/src/mongo/shell/db.js#L913-L978

-> we should report both the configured size and the actual size in both printReplicationInfo() and getReplicationInfo(), and we should be using MB instead of bytes properly