## Bug description

When filtering insights by active feature flags, and trying to select a single feature flag (by using a `contains` selector), events are not being correctly filter (i.e. no events are returned). This presumably happens because the `active_feature_flags` attribute is stored as an array and the operator does not work properly on CH.

## Expected behavior

Relevant events should be loaded.

## How to reproduce

1. Create an insights graph, filter by "Active feature flags" using a contain selector.

Alternatively, just open [this graph](https://app.posthog.com/insights?actions=%5B%7B%22id%22%3A1578%2C%22name%22%3A%22created%20action%22%2C%22type%22%3A%22actions%22%2C%22order%22%3A0%7D%5D&events=%5B%5D&new_entity=%5B%5D&interval=week&date_from=-90d&breakdown=false&breakdown_type&properties=%5B%7B%22key%22%3A%22%24active_feature_flags%22%2C%22value%22%3A%22actions-ux-201012%22%2C%22operator%22%3A%22icontains%22%2C%22type%22%3A%22event%22%7D%5D).

## Environment

Cloud latest version.


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

CC @timgl 

ee/clickhouse/models/cohort.py
filters = []
    params: Dict[str, Any] = {}
    for group_idx, group in enumerate(cohort.groups):
        if group.get("action_id"):
            action = Action.objects.get(pk=group["action_id"], team_id=cohort.team.pk)
            action_filter_query, action_params = format_action_filter(action)
            extract_person = "SELECT distinct_id FROM events WHERE team_id = %(team_id)s AND {query}".format(
                query=action_filter_query
            )
            params = {**params, **action_params}
            filters.append("distinct_id IN (" + extract_person + ")")
        elif group.get("properties"):
            from ee.clickhouse.models.property import prop_filter_json_extract
            filter = Filter(data=group)
            query = ""
            for idx, prop in enumerate(filter.properties):
                filter_query, filter_params = prop_filter_json_extract(
                    prop=prop, idx=idx, prepend="{}_{}_{}_person".format(cohort.pk, group_idx, idx)
                )
                params = {**params, **filter_params}
                query += " {}".format(filter_query)
            filters.append("person_id IN {}".format(GET_LATEST_PERSON_ID_SQL.format(query=query)))
    joined_filter = " OR ".join(filters)
    return joined_filter, params
def format_filter_query(cohort: Cohort) -> Tuple[str, Dict[str, Any]]: