## Bug description

When calculating Trends results with an aggregated (e.g. single output, like big number) display type, WAU/MAU don't work. This is because we have an `ACTIVE_USERS_SQL` query for time series display types, but we don't have a version of this for aggregated display types. (See ZEN-1043.)

## How to reproduce

1. Create an insight with a single WAU or MAU series.
2. Switch display type to "Number".
3. Open the "Debug ClickHouse queries" modal from the command palette.
4. See `COUNT(*)` instead of `COUNT(DISTINCT person_id)`.

#### *Thank you* for your bug report – we love squashing them!

posthog/queries/trends/trends_event_query.py
entity_params, entity_format_params = get_entity_filtering_params(
            entity=self._entity,
            team_id=self._team_id,
            table_name=self.EVENT_TABLE_ALIAS,
            person_properties_mode=PersonPropertiesMode.DIRECT_ON_EVENTS
            if self._using_person_on_events
            else PersonPropertiesMode.USING_PERSON_PROPERTIES_COLUMN,
        )
        return entity_format_params["entity_query"], entity_params
    @cached_property
    def _person_query(self):
        return PersonQuery(
            self._filter,
            self._team_id,
            self._column_optimizer,
            extra_fields=self._extra_person_fields,
            entity=self._entity,
        )