## 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
properties={"$session_id": 4, "$some_property": "value1"},
            timestamp="2020-01-02 00:06:45",
        )
        
        with freeze_time("2020-01-04T13:00:01Z"):
            daily_response = Trends().run(
                Filter(
                    data={
                        "display": TRENDS_TABLE,
                        "interval": "week",
                        "breakdown": "$some_prop",
                        "breakdown_type": "person",
                        "events": [{"id": "sign up", "math": "median", "math_property": "$session_duration"}],
                    }
                ),
                self.team,
            )
        
        
        self.assertEqual([resp["breakdown_value"] for resp in daily_response], ["another_val", "some_val"])
        self.assertEqual([resp["aggregated_value"] for resp in daily_response], [10.0, 5.0])
    @test_with_materialized_columns(["$math_prop", "$some_property"])
    def test_trends_breakdown_with_math_func(self):
        with freeze_time("2020-01-01 00:06:34"):
            for i in range(20):
                _create_person(team_id=self.team.pk, distinct_ids=[f"person{i}"])
                _create_event(
                    team=self.team,
                    event="sign up",
                    distinct_id=f"person{i}",