## 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/person_query.py
if not isinstance(self._filter, Filter):
            return "", {}
        if self._filter.search:
            prop_group = PropertyGroup(
                type=PropertyOperatorType.AND,
                values=[Property(key="email", operator="icontains", value=self._filter.search, type="person")],
            )
            search_clause, params = parse_prop_grouped_clauses(
                self._team_id,
                prop_group,
                prepend=f"search_{prepend}",
                has_person_id_joined=False,
                group_properties_joined=False,
                person_properties_mode=PersonPropertiesMode.DIRECT,
                _top_level=False,
            )
            distinct_id_param = f"distinct_id_{prepend}"
            distinct_id_clause = f"""
            id IN (
                SELECT person_id FROM ({get_team_distinct_ids_query(self._team_id)}) where distinct_id = %({distinct_id_param})s
            )
            """
            params.update({distinct_id_param: self._filter.search})
            return f"AND (({search_clause}) OR ({distinct_id_clause}))", params
        return "", {}
    def _get_distinct_id_clause(self) -> Tuple[str, Dict]: