## 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
team=self.team,
                event="sign up",
                distinct_id="blabla2",
                properties={"$current_url": "second url", "$browser": "Chrome", "$os": "Windows"},
            )
        with freeze_time("2020-01-05T13:01:01Z"):
            response = Trends().run(
                Filter(
                    data={
                        "date_from": "-14d",
                        "breakdown": "$current_url",
                        "events": [
                            {
                                "id": "sign up",
                                "name": "sign up",
                                "type": "events",
                                "order": 0,
                                "properties": [{"key": "$os", "value": "Mac"}],
                            }
                        ],
                        "properties": {
                            "type": "OR",
                            "values": [{"key": "$browser", "value": "Firefox"}, {"key": "$os", "value": "Windows"}],
                        },
                    }
                ),
                self.team,
            )
        response = sorted(response, key=lambda x: x["label"])
        self.assertEqual(response[0]["label"], "sign up - second url")