## 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)`.

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posthog/queries/test/test_trends.py
@test_with_materialized_columns(person_properties=["name"])
    def test_breakdown_by_person_property_pie(self):
        self._create_multiple_people()
        with freeze_time("2020-01-04T13:01:01Z"):
            event_response = Trends().run(
                Filter(
                    data={
                        "date_from": "-14d",
                        "breakdown": "name",
                        "breakdown_type": "person",
                        "display": "ActionsPie",
                        "events": [
                            {
                                "id": "watched movie",
                                "name": "watched movie",
                                "type": "events",
                                "order": 0,
                                "math": "dau",
                            }
                        ],
                    }
                ),
                self.team,
            )
            event_response = sorted(event_response, key=lambda resp: resp["breakdown_value"])
            self.assertDictContainsSubset({"breakdown_value": "person1", "aggregated_value": 1}, event_response[0])
            self.assertDictContainsSubset({"breakdown_value": "person2", "aggregated_value": 1}, event_response[1])
            self.assertDictContainsSubset({"breakdown_value": "person3", "aggregated_value": 1}, event_response[2])
    @test_with_materialized_columns(person_properties=["name"])
    def test_filter_test_accounts_cohorts(self):