## 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_events()
        with freeze_time("2020-01-04T13:00:01Z"):
            daily_response = Trends().run(
                Filter(
                    data={"display": TRENDS_TABLE, "interval": "week", "events": [{"id": "sign up", "math": "dau"}]}
                ),
                self.team,
            )
        with freeze_time("2020-01-04T13:00:01Z"):
            weekly_response = Trends().run(
                Filter(data={"display": TRENDS_TABLE, "interval": "day", "events": [{"id": "sign up", "math": "dau"}]}),
                self.team,
            )
        self.assertEqual(daily_response[0]["aggregated_value"], 1)
        self.assertEqual(daily_response[0]["aggregated_value"], weekly_response[0]["aggregated_value"])
    @test_with_materialized_columns(["$math_prop"])
    def test_trends_single_aggregate_math(self):
        _create_person(
            team_id=self.team.pk, distinct_ids=["blabla", "anonymous_id"], properties={"$some_prop": "some_val"}
        )
        with freeze_time("2020-01-01 00:06:34"):
            _create_event(team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 1})
            _create_event(team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 1})
            _create_event(team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 1})
            _create_event(team=self.team, event="sign up", distinct_id="blabla", properties={"$math_prop": 2})