## 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
_create_event(
                team=self.team,
                event="sign up",
                distinct_id="blabla",
                properties={"$some_property": "value", "$bool_prop": False},
            )
            _create_event(team=self.team, event="sign up", distinct_id="anonymous_id", properties={"$bool_prop": False})
            _create_event(team=self.team, event="sign up", distinct_id="blabla")
        with freeze_time(freeze_args[2]):
            _create_event(
                team=self.team,
                event="sign up",
                distinct_id="blabla",
                properties={"$some_property": "other_value", "$some_numerical_prop": 80},
            )
            _create_event(team=self.team, event="no events", distinct_id="blabla")
            
            _create_event(
                team=secondTeam, event="sign up", distinct_id="blabla", properties={"$some_property": "other_value"}
            )
        _create_action(team=self.team, name="no events")
        sign_up_action = _create_action(team=self.team, name="sign up")
        return sign_up_action, person
    def _create_breakdown_events(self):
        freeze_without_time = ["2020-01-02"]
        with freeze_time(freeze_without_time[0]):
            for i in range(25):
                _create_event(team=self.team, event="sign up", distinct_id="blabla", properties={"$some_property": i})
        _create_action(team=self.team, name="sign up")
    def _create_event_count_per_user_events(self):