## 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/test/test_trends.py
# 
        # 
        self._create_multiple_people()
        with freeze_time("2020-01-04"):
            response = Trends().run(
                Filter(
                    data={
                        "properties": [{"key": "name", "value": "person1", "type": "person"}],
                        "events": [{"id": "watched movie"}],
                    }
                ),
                self.team,
            )
        self.assertEqual(response[0]["labels"][4], "1-Jan-2020")
        self.assertEqual(response[0]["data"][4], 1.0)
        self.assertEqual(response[0]["labels"][5], "2-Jan-2020")
        self.assertEqual(response[0]["data"][5], 0)
        with freeze_time("2020-01-04"):
            response = Trends().run(
                Filter(
                    data={
                        "properties": [{"key": "name", "value": "1", "type": "event"}],
                        "events": [{"id": "watched movie"}],