## 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/action.py
filters = model_to_dict(step)
    params = {}
    conditions = []
    if filters.get("selector"):
        selector = Selector(filters["selector"], escape_slashes=False)
        params["{}selector_regex".format(prepend)] = _create_regex(selector)
        conditions.append("match(elements_chain, %({}selector_regex)s)".format(prepend))
    if filters.get("tag_name"):
        params["{}tag_name_regex".format(prepend)] = r"(^|;){}(\.|$|;|:)".format(filters["tag_name"])
        conditions.append("match(elements_chain, %({}tag_name_regex)s)".format(prepend))
    attributes: Dict[str, str] = {}
    for key in ["href", "text"]:
        if filters.get(key):
            attributes[key] = re.escape(filters[key])
    if len(attributes.keys()) > 0:
        params["{}attributes_regex".format(prepend)] = ".*?({}).*?".format(
            ".*?".join(['{}="{}"'.format(key, value) for key, value in attributes.items()])
        )
        conditions.append("match(elements_chain, %({}attributes_regex)s)".format(prepend))
    return (conditions, params)