Vector clock gossiping happens for every incoming and outgoing request, including from mongos to mongod and mongod to mongod. There are a few small optimizations we can make to it:

1. Skip sending a signature when the client is authorized to skip clock validation, e.g. all inter node communication. We can treat no signature the same as the "dummy signed" signature.
2. Skip checking authorization when gossiping out if the client is internal, like the assumption we make when gossiping in from an internal client.
3. Don't check authorization twice, once when gossiping in and again when gossiping out in the command entry point, since both calls happen on the same side as the call to AuthorizationSession::startRequest() (for mongos and mongod).