## Bug description

Currently, decide endpoint takes 10+ seconds on kea.js.org.

This means that for first-time visitors autocapture nor session recording will be turned on for that long - losing valuable information.

When measuring this yesterday via shell ([slack thread](https://posthog.slack.com/archives/C0113360FFV/p1604951621008400)), the culprit was feature flags cohort checking. In this case, the cohort user was checked against was defined against the following action:

![Screenshot from 2020-11-10 11-41-32](https://user-images.githubusercontent.com/148820/98657215-49582e80-234a-11eb-9669-37d55e0d23bd.png)

Which currently looks through events of the data for that team.

## Expected behavior

Decide endpoint should use cached/materialized cohort ownership rather than calculating it on the fly.

## How to reproduce

1. Create an action with some selector
2. Create a cohort for has done action at any point
3. Create a feature flag using the cohort.
4. Measure /decide endpoint latency

## Environment

Cloud 

## Additional context

cc @EDsCODE who made it not time out by https://github.com/PostHog/posthog/pull/2299

#### *Thank you* for your bug report – we love squashing them!
ee/clickhouse/sql/person.py
PERSON_TREND_SQL = """
SELECT DISTINCT distinct_id FROM events WHERE team_id = %(team_id)s {entity_filter} {filters} {parsed_date_from} {parsed_date_to} {person_filter}
"""
PEOPLE_THROUGH_DISTINCT_SQL = """
SELECT id, created_at, team_id, properties, is_identified, groupArray(distinct_id) FROM (
    {latest_person_sql}
) as person INNER JOIN (
    SELECT DISTINCT person_id, distinct_id FROM person_distinct_id WHERE distinct_id IN ({content_sql}) AND team_id = %(team_id)s
) as pdi ON person.id = pdi.person_id
WHERE team_id = %(team_id)s
GROUP BY id, created_at, team_id, properties, is_identified
LIMIT 200 OFFSET %(offset)s
"""
PEOPLE_SQL = """
SELECT id, created_at, team_id, properties, is_identified, groupArray(distinct_id) FROM (
    {latest_person_sql}
) as person INNER JOIN (
    SELECT DISTINCT person_id, distinct_id FROM person_distinct_id WHERE person_id IN ({content_sql}) AND team_id = %(team_id)s
) as pdi ON person.id = pdi.person_id GROUP BY id, created_at, team_id, properties, is_identified
LIMIT 200 OFFSET %(offset)s 
"""
GET_DISTINCT_IDS_BY_PROPERTY_SQL = """
SELECT distinct_id FROM person_distinct_id WHERE person_id IN
(
    SELECT id
    FROM person
    WHERE team_id = %(team_id)s {filters}
) AND team_id = %(team_id)s
"""