## Bug description

We've had a user create a funnel with Korean characters and 17 steps, which causes this issue:
![image](https://user-images.githubusercontent.com/1727427/120301818-8c212a00-c2cd-11eb-8b00-7ba242e4a9ab.png)

## Expected behavior

We should send requests to api/insight/funnel using POST instead of GET.

## How to reproduce

1.
2.
3.

## Environment

- [ ] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: _please provide_

## Additional context



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

posthog/utils.py
cache_key_value = get_client().get("@posthog-plugin-server/enabled-job-queues")
    if cache_key_value:
        qs = cache_key_value.decode("utf-8").replace('"', "")
        return qs.split(",")
    return None
def get_redis_info() -> Mapping[str, Any]:
    return get_client().info()
def get_redis_queue_depth() -> int:
    return get_client().llen("celery")
def queryset_to_named_query(qs: QuerySet, prepend: str = "") -> Tuple[str, dict]:
    raw, params = qs.query.sql_with_params()
    arg_count = 0
    counter = count(arg_count)
    new_string = re.sub(r"%s", lambda _: f"%({prepend}_arg_{str(next(counter))})s", raw)
    named_params = {}
    for idx, param in enumerate(params):
        named_params.update({f"{prepend}_arg_{idx}": param})
    return new_string, named_params
def get_instance_realm() -> str:
    """
    Returns the realm for the current instance. `cloud` or `hosted` or `hosted-clickhouse`.
    """
    if settings.MULTI_TENANCY:
        return "cloud"
    elif os.getenv("HELM_INSTALL_INFO", False):
        return "hosted-clickhouse"
    else:
        return "hosted"
def get_available_social_auth_providers() -> Dict[str, bool]: