mongoreplay playback includes stale clusterTime and causal consistency 'afterClusterTime' read concern field

As mongoreplay replays traffic largely unaltered, it will use stale $clusterTime and afterClusterTime (in read concern) fields. As a replay, the times are independent of the target cluster (though earlier than time in the target cluster, assuming synchronized clocks.

We should better understand the implication of this on replay, and whether the fields should be stripped, modified, or left alone.