## 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
distinct_id="blabla",
                properties={"$current_url": "second url", "$browser": "Chrome", "$os": "Windows"},
            )
        with freeze_time("2020-01-05T13:01:01Z"):
            response = ClickhouseTrends().run(
                Filter(
                    data={
                        "date_from": "-14d",
                        "breakdown": "$current_url",
                        "events": [
                            {
                                "id": "sign up",
                                "name": "sign up",
                                "type": "events",
                                "order": 0,
                                "properties": [{"key": "$os", "value": "Mac"}],
                            },
                        ],
                        "properties": [{"key": "$browser", "value": "Firefox"}],
                    }
                ),
                self.team,
            )
        self.assertEqual(response[0]["label"], "sign up - second url")
        self.assertEqual(response[1]["label"], "sign up - first url")
        self.assertEqual(sum(response[0]["data"]), 1)
        self.assertEqual(response[0]["breakdown_value"], "second url")
        self.assertEqual(sum(response[1]["data"]), 1)
        self.assertEqual(response[1]["breakdown_value"], "first url")
    def test_dau_with_breakdown_filtering(self):