## 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
regex = r""
    for idx, tag in enumerate(selector.parts):
        if tag.data.get("tag_name") and isinstance(tag.data["tag_name"], str):
            regex += tag.data["tag_name"]
        if tag.data.get("attr_class__contains"):
            regex += r".*?\.{}".format(r"\..*?".join(sorted(tag.data["attr_class__contains"])))
        if tag.ch_attributes:
            regex += ".*?"
            for key, value in sorted(tag.ch_attributes.items()):
                regex += '{}="{}".*?'.format(key, value)
        regex += r"([-_a-zA-Z0-9\.]*?)?($|;|:([^;^\s]*(;|$|\s)))"
        if tag.direct_descendant:
            regex += ".*"
    return regex
def filter_element(step: ActionStep, prepend: str = "") -> Tuple[List[str], Dict]: