The scope of user events to be rejoined with the latest product
catalog. If the rejoining aims at reducing number of unjoined
events, set UserEventRejoinScope to UNJOINED_EVENTS. If the
rejoining aims at correcting product catalog information in joined
events, set UserEventRejoinScope to JOINED_EVENTS. If all events
needs to be rejoined, set UserEventRejoinScope to
USER_EVENT_REJOIN_SCOPE_UNSPECIFIED.