## 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/trends/breakdown.py
if self.entity.math in PROPERTY_MATH_FUNCTIONS and self.entity.math_property == "$session_duration":
                
                
                content_sql = SESSION_DURATION_BREAKDOWN_AGGREGATE_QUERY_SQL.format(
                    breakdown_filter=breakdown_filter,
                    person_join=person_join_condition,
                    groups_join=groups_join_condition,
                    sessions_join_condition=sessions_join_condition,
                    aggregate_operation=aggregate_operation,
                    breakdown_value=breakdown_value,
                    event_sessions_table_alias=SessionQuery.SESSION_TABLE_ALIAS,
                )
            elif self.entity.math in COUNT_PER_ACTOR_MATH_FUNCTIONS:
                content_sql = VOLUME_PER_ACTOR_BREAKDOWN_AGGREGATE_SQL.format(
                    breakdown_filter=breakdown_filter,
                    person_join=person_join_condition,
                    groups_join=groups_join_condition,
                    sessions_join_condition=sessions_join_condition,
                    aggregate_operation=aggregate_operation,
                    aggregator=self.actor_aggregator,
                    breakdown_value=breakdown_value,
                )
            else:
                content_sql = BREAKDOWN_AGGREGATE_QUERY_SQL.format(
                    breakdown_filter=breakdown_filter,
                    person_join=person_join_condition,
                    groups_join=groups_join_condition,
                    sessions_join_condition=sessions_join_condition,
                    aggregate_operation=aggregate_operation,
                    breakdown_value=breakdown_value,