FleStats track update and compaction related metrics that are incremented when the mongod/shard-role update and compaction commands are run. But, FleStats are never modified in mongos/the router-role so we don't track any metrics there.

If we want to track router-role metrics to expose from mongos/the router for FLE update and compaction, we should track the stats there and expose a router-role associated instance of FleStats.