## 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
("[4.95,10.05]", 2.0, [2.0, 0.0, 0.0, 0.0]),
                    ("[10.05,15.01]", 1.0, [0.0, 1.0, 0.0, 0.0]),
                ],
            )
    @test_with_materialized_columns(person_properties=["name"], verify_no_jsonextract=False)
    def test_trends_breakdown_single_aggregate_cohorts(self):
        _create_person(team_id=self.team.pk, distinct_ids=["Jane"], properties={"name": "Jane"})
        _create_person(team_id=self.team.pk, distinct_ids=["John"], properties={"name": "John"})
        _create_person(team_id=self.team.pk, distinct_ids=["Jill"], properties={"name": "Jill"})
        cohort1 = _create_cohort(
            team=self.team,
            name="cohort1",
            groups=[{"properties": [{"key": "name", "value": "Jane", "type": "person"}]}],
        )
        cohort2 = _create_cohort(
            team=self.team,
            name="cohort2",
            groups=[{"properties": [{"key": "name", "value": "John", "type": "person"}]}],
        )
        cohort3 = _create_cohort(
            team=self.team,
            name="cohort3",
            groups=[{"properties": [{"key": "name", "value": "Jill", "type": "person"}]}],
        )
        with freeze_time("2020-01-01 00:06:34"):
            _create_event(
                team=self.team,
                event="sign up",
                distinct_id="John",
                properties={"$some_property": "value", "$browser": "Chrome"},