In addition to SERVER-97164 (which runs the NITL cpp integration tests), we also want to test one layer lower (the AsyncDBClient). Enable the transport_integration_test with gRPC by converting the 
AsyncClientIntegrationTest to inherit the transport layer from a base class, rather than using the default egress layer off of the TransportLayer as it does now. Also make the required resmoke changes to run the integration tests in resmoke (rather than deferring this work to SERVER-97164).