Single-document lookups apply a post-read shard filter to drop orphans. When the LocalLookupEligibility already resolves locality from the documentKey's shard key (ShardedClusterLocalLookupEligibility, used by change-stream updateLookup), that ownership check makes the post-read filter redundant. Add LocalLookupEligibility::checksShardKeyOwnership() and skip the filter in both the Express and SBE executors when it is set.

$search idLookup (AlwaysLocalEligibility) does not inspect a shard key, so it still applies the filter; SBE gains shard filtering via INCLUDE_SHARD_FILTER for that path.

Safe for change streams because the SBE change-streams updateLookup path already relies on per-shard _id uniqueness (no same-_id orphan), so a Local decision uniquely identifies the owned document.