## Bug description

Trying to look at insights for feature flags no longer works (see screenshot below).

<img width="1329" alt="" src="https://user-images.githubusercontent.com/5864173/100642031-de24cb00-32fd-11eb-88b4-047c4f82124f.png">


Removing the breakdown works but then you can't see the difference between the binary values.

![image](https://user-images.githubusercontent.com/5864173/100642046-e2e97f00-32fd-11eb-8ae5-4238f899c8b8.png)


## Expected behavior

Insights should be shown as before.


## How to reproduce

1. Click on the insights link on any feature flag row.

## Environment

Cloud (Clickhouse).

## Additional context



#### *Thank you* for your bug report – we love squashing them!

ee/clickhouse/queries/trends/breakdown.py
def _serialize_breakdown(self, entity: Entity, filter: Filter, team_id: int):
        if isinstance(filter.breakdown, list) and "all" in filter.breakdown:
            result = []
            filter.breakdown = filter.breakdown if filter.breakdown and isinstance(filter.breakdown, list) else []
            filter.breakdown.remove("all")
            
            if filter.breakdown:
                result.extend(self._format_breakdown_query(entity, filter, team_id))
            filter.breakdown = ["all"]
            all_result = self._format_breakdown_query(entity, filter, team_id)
            result.extend(all_result)
        else:
            result = self._format_breakdown_query(entity, filter, team_id)
        return result
    def _format_breakdown_query(self, entity: Entity, filter: Filter, team_id: int) -> List[Dict[str, Any]]: