## 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
"person3": [
                {
                    "event": "watched movie",
                    "timestamp": datetime(2020, 1, 1, 12),
                    "properties": {"order": "1", "name": "3"},
                },
                {
                    "event": "watched movie",
                    "timestamp": datetime(2020, 1, 2, 12),
                    "properties": {"order": "2", "name": "3"},
                },
                {
                    "event": "watched movie",
                    "timestamp": datetime(2020, 1, 3, 12),
                    "properties": {"order": "2", "name": "3"},
                },
            ],
            "person4": [
                {
                    "event": "watched movie",
                    "timestamp": datetime(2020, 1, 5, 12),
                    "properties": {"order": "1", "name": "4"},
                }
            ],
        }
        journeys_for(events_by_person=journey, team=self.team)
        return (person1, person2, person3, person4)
    @test_with_materialized_columns(person_properties=["name"])
    @snapshot_clickhouse_queries
    def test_person_property_filtering(self):