ReplSetTest starts up multiple mongods and ShardingTest starts up multiple ReplSetTest's but each are done serially. Test startup could probably be sped up significantly by doing some of this work in parallel. Rather than truly doing this in parallel, we can simply delay connecting to each node until we've started up all of the nodes in a ReplSetTest. Similarly, we can delay calling "awaitSecondaryNodes()" for each ReplSetTest until we've called initiate on each ReplSetTest. This allows most of startup and initiate to be done in parallel both within one ReplSetTest and among multiple ReplSetTests in a ShardingTest.