In local development StatsD is raising `OSError: [WinError 10049] The requested address is not valid in its context` when env variable `STATSD_HOST` is not set. This seems to just be a Windows issue as the error suggests, because I can't get it to happen inside Docker.

This is happening because the default empty string of `settings.STATSD_HOST` gets set as the default host of `statsd.Connection`, and the empty string is not a valid host name in Windows.

https://github.com/PostHog/posthog/blob/1357df0c137e36478be19a1b8739dcdba93d2327/posthog/settings.py#L181
https://github.com/PostHog/posthog/blob/1ec12f26e707489e77077be029ddb79ceeefd944/posthog/celery.py#L35

StatsD sets the default `host` value to `'localhost'`, and restoring this default fixes the errors. I can make a PR tomorrow, but just wanted to check on this:
https://github.com/PostHog/posthog/blob/1357df0c137e36478be19a1b8739dcdba93d2327/posthog/settings.py#L217-L219

I can change it to `if os.environ.get("STATSD_HOST", False):`, but it might make more sense as a separate env variable like `STATSD_ENABLED`. My only concern with that is it's probably a breaking change. Are there any better options?



posthog/settings.py
"""
Django settings for posthog project.
Generated by 'django-admin startproject' using Django 2.2.5.
For more information on this file, see
https://docs.djangoproject.com/en/2.2/topics/settings/
For the full list of settings and their values, see
https://docs.djangoproject.com/en/2.2/ref/settings/
"""
import os
import shutil
import sys
from distutils.util import strtobool
from typing import Dict, List, Sequence
from urllib.parse import urlparse
import dj_database_url
import sentry_sdk
from django.core.exceptions import ImproperlyConfigured
from kombu import Exchange, Queue
from sentry_sdk.integrations.celery import CeleryIntegration
from sentry_sdk.integrations.django import DjangoIntegration
from sentry_sdk.integrations.redis import RedisIntegration
def get_env(key):
    try:
        return os.environ[key]
    except KeyError:
        raise ImproperlyConfigured(f'The environment var "{key}" is absolutely required to run this software')
def get_list(text: str) -> List[str]: