## 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/sql.py
-- Generates all the intervals/ticks in the date range
                -- NOTE: we build this range by including successive intervals back from the
                --       upper bound, then including the lower bound in the query also.
                SELECT
                    {interval}(
                        toDateTime(%(date_to)s, %(timezone)s) - number * %(seconds_in_interval)s
                    ) as day_start
                FROM numbers({num_intervals})
                UNION ALL
                SELECT {interval}(toDateTime(%(date_from)s, %(timezone)s)) as day_start
            ) as ticks
            -- Zero fill for all values for the specified breakdown
            CROSS JOIN
                (
                    SELECT breakdown_value
                    FROM (
                        SELECT %(values)s as breakdown_value
                    ) ARRAY JOIN breakdown_value
                ) as sec
            ORDER BY breakdown_value, day_start
            UNION ALL
            {inner_sql}
        )
    )
    GROUP BY day_start, breakdown_value
    ORDER BY breakdown_value, day_start
)
GROUP BY breakdown_value
ORDER BY breakdown_value
"""