## 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_person(
            team_id=self.team.pk,
            distinct_ids=["person4"],
            properties={"email": "test3@posthog.com", "$os": "android", "$browser": "safari"},
        )
        _create_person(
            team_id=self.team.pk,
            distinct_ids=["person5"],
            properties={"email": "test4@posthog.com", "$os": "android", "$browser": "safari"},
        )
        _create_person(
            team_id=self.team.pk,
            distinct_ids=["person6"],
            properties={"email": "test5@posthog.com", "$os": "android", "$browser": "safari"},
        )
        journeys_for(
            team=self.team,
            create_people=False,
            events_by_person={
                "person1": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
                "person2": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
                "person3": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
                "person32": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
                "person4": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
                "person5": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
                "person6": [{"event": "sign up", "properties": {"key": "val"}, "timestamp": datetime(2020, 5, 1, 0)}],
            },
        )
        response = Trends().run(