Make sharded clusters take the local change-stream updateLookup path under featureFlagChangeStreamOptimizedUpdateLookup. The production eligibility factory currently declines on a sharded node, so flag-on sharded streams always fall through to the routed aggregation lookup.

What

• Flip the eligibility factory so a sharded node produces the real sharded eligibility (using the node's shard id); the replica-set path is unchanged.
• Let StaleConfig, StaleDbVersion, and ShardCannotRefreshDueToLocksHeld propagate out of the Express lookup body so the eligibility's router refresh and retry handle them; keep NamespaceNotFound and CollectionUUIDMismatch mapping to a null fullDocument. Update the affected Express unit tests to the new behavior.
• Add a router-level refresh-and-retry unit test for the sharded eligibility (stale then fresh routing info; the body throws StaleConfig once then succeeds).
• Add sharding integration jstests under jstests/sharding/query/change_streams covering a chunk migration race, the orphan window, a collection after resharding, a collection after refining the shard key, database-level and cluster-level streams, and collation. Each asserts that flag-on output matches flag-off output.

Acceptance

• On a sharded cluster with the flag on, a locally owned documentKey is served by the local path, and migration, resharding, and shard-key-refine races still produce the correct document.
• All new and existing sharding change-stream updateLookup jstests pass with the flag on and with the flag off.