## 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
# 
        _create_person(
            team_id=self.team.pk, distinct_ids=["blabla", "anonymous_id"], properties={"$some_prop": "some_val"}
        )
        _create_event(
            team=self.team,
            event="$pageview",
            distinct_id="blabla",
            properties={"$host": "app.example.com"},
            timestamp="2020-01-03T12:00:00Z",
        )
        with freeze_time("2020-01-04T13:01:01Z"):
            response = Trends().run(
                Filter(
                    data={
                        "events": [
                            {
                                "id": "$pageview",
                                "properties": [{"key": "$host", "operator": "icontains", "value": ".com"}],
                            }
                        ],
                        "properties": [{"key": "$host", "value": ["app.example.com", "another.com"]}],
                        "breakdown": "$some_prop",
                        "breakdown_type": "person",
                    }
                ),
                self.team,
            )
        self.assertEqual(response[0]["count"], 1)
    #