## 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
if self._should_join_sessions
                else ""
            )
            + (
                f", {self.SESSION_TABLE_ALIAS}.$session_id as $session_id"
                if self._should_join_sessions
                and "$session_id" not in self._extra_event_properties
                and "$session_id" not in self._column_optimizer.event_columns_to_query
                else ""
            )
            + (f", {self.EVENT_TABLE_ALIAS}.distinct_id as distinct_id" if self._aggregate_users_by_distinct_id else "")
            + (f", {self.EVENT_TABLE_ALIAS}.person_id as person_id" if self._using_person_on_events else "")
            + (
                " ".join(
                    f", {self.EVENT_TABLE_ALIAS}.{column_name} as {column_name}" for column_name in self._extra_fields
                )
            )
            + (self._get_extra_person_columns())
        )
        if self._using_person_on_events:
            for column_name in sorted(self._column_optimizer.person_on_event_columns_to_query):
                _fields += f', {self.EVENT_TABLE_ALIAS}."{column_name}" as "{column_name}"'
        if self._using_person_on_events and groups_on_events_querying_enabled():
            for column_name in sorted(self._column_optimizer.group_on_event_columns_to_query):
                _fields += f', {self.EVENT_TABLE_ALIAS}."{column_name}" as "{column_name}"'
        date_query, date_params = self._get_date_filter()
        self.params.update(date_params)
        prop_query, prop_params = self._get_prop_groups(
            self._filter.property_groups.combine_property_group(PropertyOperatorType.AND, self._entity.property_groups),
            person_properties_mode=PersonPropertiesMode.DIRECT_ON_EVENTS