## 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, person = self._create_events()
        action_response = Trends().run(Filter(data={"actions": [{"id": sign_up_action.id}]}), self.team)
        event_response = Trends().run(Filter(data={"events": [{"id": "sign up"}]}), self.team)
        self.assertEqual(len(action_response), 1)
        self.assertEntityResponseEqual(action_response, event_response)
    def test_trends_for_non_existing_action(self):
        with freeze_time("2020-01-04"):
            response = Trends().run(Filter(data={"actions": [{"id": 50000000}]}), self.team)
        self.assertEqual(len(response), 0)
        with freeze_time("2020-01-04"):
            response = Trends().run(Filter(data={"events": [{"id": "DNE"}]}), self.team)
        self.assertEqual(response[0]["data"], [0, 0, 0, 0, 0, 0, 0, 0])
    @test_with_materialized_columns(person_properties=["email", "bar"])
    def test_trends_regression_filtering_by_action_with_person_properties(self):