Increase replica set size and stepdown period and decrease election timeout in auto_retry_on_network_error.js

auto_retry_on_network_error.js, can fail with a NotMaster error when the same node is elected primary in successive terms. To decrease the frequency the test is failing at, add an extra node to the test's replica set, increase the replSetStepDown period, and decrease the election timeout to reduce the chance this happens. This should also significantly reduce the test's runtime.