## 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)`.

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posthog/queries/trends/total_volume.py
if filter.smoothing_intervals > 1:
                smoothing_operation = f"""
                    AVG(SUM(total))
                    OVER (
                        ORDER BY day_start
                        ROWS BETWEEN {filter.smoothing_intervals - 1} PRECEDING
                        AND CURRENT ROW
                    )"""
            else:
                smoothing_operation = "SUM(total)"
            final_query = AGGREGATE_SQL.format(
                null_sql=null_sql,
                content_sql=content_sql,
                smoothing_operation=smoothing_operation,
                aggregate="count" if filter.smoothing_intervals < 2 else "floor(count)",
            )
            return final_query, params, self._parse_total_volume_result(filter, entity, team)
    def _parse_total_volume_result(self, filter: Filter, entity: Entity, team: Team) -> Callable:
        def _parse(result: List) -> List:
            parsed_results = []
            if result is not None:
                for stats in result:
                    parsed_result = parse_response(stats, filter)
                    parsed_result.update({"persons_urls": self._get_persons_url(filter, entity, team.pk, stats[0])})
                    parsed_results.append(parsed_result)
                    parsed_result.update({"filter": filter.to_dict()})
            return parsed_results
        return _parse
    def _parse_aggregate_volume_result(self, filter: Filter, entity: Entity, team_id: int) -> Callable: