Change Jepsen tasks running in Evergreen to use mongobridge

With the changes from https://github.com/jepsen-io/mongodb/pull/9, it is now possible to run MongoDB's Jepsen tests using mongobridge rather than iptables for the networking partitioning. This means it is no longer necessary to use LXC containers in Evergreen to provide virtualization. Establishing SSH connections to the LXC containers has seemingly been unreliable with there being ~220 "System Failure"-related BF/BFG tickets (of ~840 total).

We should also consider preemptively vendoring https://github.com/jepsen-io/jepsen and https://github.com/aphyr/dom-top as branches in the 10gen/jepsen repository in case we ever depend on a snapshotted version of the jepsen-io/jepsen repository. Leiningen supports checkout dependencies so we can easily compile the project using our vendored copies.