## 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
sign_up_action = self._create_maths_events(values)
        action_response = Trends().run(
            Filter(
                data={"actions": [{"id": sign_up_action.id, "math": math_property, "math_property": "some_number"}]}
            ),
            self.team,
        )
        event_response = Trends().run(
            Filter(data={"events": [{"id": "sign up", "math": math_property, "math_property": "some_number"}]}),
            self.team,
        )
        # 
        self.assertAlmostEqual(action_response[0]["data"][-1], expected_value, delta=0.5)
        self.assertEntityResponseEqual(action_response, event_response)
    @test_with_materialized_columns(["some_number"])
    def test_sum_filtering(self):
        self._test_math_property_aggregation("sum", values=[2, 3, 5.5, 7.5], expected_value=18)
    @test_with_materialized_columns(["some_number"])
    def test_avg_filtering(self):
        self._test_math_property_aggregation("avg", values=[2, 3, 5.5, 7.5], expected_value=4.5)
    @test_with_materialized_columns(["some_number"])
    def test_min_filtering(self):
        self._test_math_property_aggregation("min", values=[2, 3, 5.5, 7.5], expected_value=2)
    @test_with_materialized_columns(["some_number"])
    def test_max_filtering(self):
        self._test_math_property_aggregation("max", values=[2, 3, 5.5, 7.5], expected_value=7.5)
    @test_with_materialized_columns(["some_number"])
    def test_median_filtering(self):