Integration tests hard-code expectations for mongod port, auth params, etc. mongoreplay also uses a different port setting. This makes it hard to easily/quickly test against different configurations.
Many drivers projects pick up a MongoDB connection string URI from the environment if available. We should make the same change for tools and eventually migrate Evergreen testing to use that instead of a hard-coded host/port. That will allow us to expand our Evergreen testing to many more versions/topologies using mongo-orchestration and the driver evergreen tools.