## Bug description

When going to instance status > internal metrics and refreshing the dashboard, the loading fails

https://user-images.githubusercontent.com/148820/120655500-693c7480-c48b-11eb-8c75-6afd4c967506.mp4

## Expected behavior

It reloads successfully

## How to reproduce

See above

## Environment

- [x] PostHog Cloud
- [x] self-hosted PostHog, version/commit: latest

## Additional context

Seems the cause is that "refresh" requests data from `/api/insight/trends` vs getting it from `/api/dashboard/id` as on first load.

Relates to #3609  

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posthog/tasks/update_cache.py
import importlib
import json
import logging
import os
from typing import Any, Dict, List, Optional, Union
from celery import group
from dateutil.relativedelta import relativedelta
from django.core.cache import cache
from django.db.models import Prefetch, Q
from django.db.models.expressions import F, Subquery
from django.utils import timezone
from posthog.celery import update_cache_item_task
from posthog.constants import (
    INSIGHT_FUNNELS,
    INSIGHT_PATHS,
    INSIGHT_RETENTION,
    INSIGHT_SESSIONS,
    INSIGHT_STICKINESS,