Kill / restart the replicator periodically. We can stop a process at any time with a code, as we do here}https://github.com/mongodb/mongo/blob/0865fcb3162a72495c4259b80893e9b74b1069ea/buildscripts/resmokelib/testing/fixtures/replicator.py#L89. We may want to extend the ReplicatorFixture as well and maybe add some methods on it to kill / restart so that the hook doesn't have to know the details of the fixture and update the fixture's state variables.