## 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
person_properties={"name": "person6"},
            timestamp=datetime(2020, 1, 1, 12),
        )
        _create_event(
            team=self.team,
            event="watched movie",
            distinct_id="person7",
            person_id="00000000-0000-0000-0000-000000000000",
            person_properties={"name": "person2"},
            timestamp=datetime(2020, 1, 1, 12),
        )
        with freeze_time("2020-01-04T13:01:01Z"):
            event_response = Trends().run(
                Filter(
                    data={
                        "date_from": "-14d",
                        "breakdown": "name",
                        "breakdown_type": "person",
                        "events": [{"id": "watched movie", "name": "watched movie", "type": "events", "order": 0}],
                    }
                ),
                self.team,
            )
        self.assertListEqual(
            sorted(res["breakdown_value"] for res in event_response), ["person1", "person2", "person3"]
        )
        for response in event_response:
            if response["breakdown_value"] == "person1":
                self.assertEqual(response["count"], 1)
                self.assertEqual(response["label"], "watched movie - person1")