## 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
self._create_breakdown_events()
        with freeze_time("2020-01-04T13:01:01Z"):
            response = Trends().run(
                Filter(
                    data={
                        "date_from": "-14d",
                        "breakdown": "$some_property",
                        "events": [{"id": "sign up", "name": "sign up", "type": "events", "order": 0}],
                    }
                ),
                self.team,
            )
        self.assertEqual(len(response), 25)  # 
    @test_with_materialized_columns(event_properties=["order"], person_properties=["name"])
    def test_breakdown_with_person_property_filter(self):
        self._create_multiple_people()
        action = _create_action(name="watched movie", team=self.team)
        with freeze_time("2020-01-04T13:01:01Z"):
            action_response = Trends().run(
                Filter(
                    data={
                        "date_from": "-14d",