New keys do not delete stale computed values

[maxg]

Adding a new key invokes the keys_apply_rules trigger and the keys_on_insert_delete_stale_computed rule.

If active is false but an active_rules row applies: keys_on_insert_delete_stale_computed does not match, then keys_apply_rules updates active to true, and the row is inserted (without applying keys_on_update_delete_stale_computed either).

Result: stale computed values that depend on the new key are not deleted.