## 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/test/test_trends.py
sign_up_action, _ = self._create_events()
        with freeze_time("2020-01-02T13:01:01Z"):
            _create_event(
                team=self.team, event="sign up", distinct_id="blabla", properties={"$some_property": "other_value"},
            )
        with freeze_time("2020-01-04T13:01:01Z"):
            action_response = ClickhouseTrends().run(
                Filter(data={"breakdown": "$some_property", "actions": [{"id": sign_up_action.id, "math": "dau"}]}),
                self.team,
            )
            event_response = ClickhouseTrends().run(
                Filter(data={"breakdown": "$some_property", "events": [{"id": "sign up", "math": "dau"}]}), self.team,
            )
        self.assertEqual(event_response[0]["label"], "sign up - value")
        self.assertEqual(event_response[1]["label"], "sign up - other_value")
        self.assertEqual(sum(event_response[0]["data"]), 1)
        self.assertEqual(event_response[0]["data"][4], 1)  
        self.assertEqual(sum(event_response[1]["data"]), 1)
        self.assertEqual(event_response[1]["data"][5], 1)
        self.assertTrue(self._compare_entity_response(action_response, event_response))