## 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._test_math_property_aggregation("median", values=range(101, 201), expected_value=150)
    @test_with_materialized_columns(["some_number"])
    def test_p90_filtering(self):
        self._test_math_property_aggregation("p90", values=range(101, 201), expected_value=190)
    @test_with_materialized_columns(["some_number"])
    def test_p95_filtering(self):
        self._test_math_property_aggregation("p95", values=range(101, 201), expected_value=195)
    @test_with_materialized_columns(["some_number"])
    def test_p99_filtering(self):
        self._test_math_property_aggregation("p99", values=range(101, 201), expected_value=199)
    @test_with_materialized_columns(["some_number"])
    def test_avg_filtering_non_number_resiliency(self):
        sign_up_action, person = self._create_events()
        _create_person(team_id=self.team.pk, distinct_ids=["someone_else"])
        _create_event(team=self.team, event="sign up", distinct_id="someone_else", properties={"some_number": 2})
        _create_event(team=self.team, event="sign up", distinct_id="someone_else", properties={"some_number": "x"})
        _create_event(team=self.team, event="sign up", distinct_id="someone_else", properties={"some_number": None})
        _create_event(team=self.team, event="sign up", distinct_id="someone_else", properties={"some_number": 8})
        action_response = Trends().run(
            Filter(data={"actions": [{"id": sign_up_action.id, "math": "avg", "math_property": "some_number"}]}),
            self.team,
        )
        event_response = Trends().run(
            Filter(data={"events": [{"id": "sign up", "math": "avg", "math_property": "some_number"}]}), self.team
        )
        self.assertEqual(action_response[0]["data"][-1], 5)
        self.assertEntityResponseEqual(action_response, event_response)
    @test_with_materialized_columns(["$some_property"])
    def test_per_entity_filtering(self):