Allow non-member state sent in room batch to resolve for historic events (MSC2716) (#12329)

Part of https://github.com/matrix-org/synapse/issues/12110

Complement test: https://github.com/matrix-org/complement/pull/354

Previously, they didn't resolve because async `filter_events_for_client`
removes all outlier state except for out-of-band membership.

And fundamentally, we have the state at these events so they shouldn't be marked as outliers.