## 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  

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

posthog/api/dashboard.py
validated_data.pop("use_template", None)  
        if validated_data.get("is_shared") and not instance.share_token:
            instance.share_token = secrets.token_urlsafe(22)
        instance = super().update(instance, validated_data)
        if "request" in self.context:
            posthoganalytics.capture(
                self.context["request"].user.distinct_id, "dashboard updated", instance.get_analytics_metadata()
            )
        return instance
    def get_items(self, dashboard: Dashboard):
        if self.context["view"].action == "list":
            return None
        items = dashboard.items.filter(deleted=False).order_by("order").all()
        self.context.update({"dashboard": dashboard})
        return DashboardItemSerializer(items, many=True, context=self.context).data
class DashboardsViewSet(StructuredViewSetMixin, viewsets.ModelViewSet):
    legacy_team_compatibility = True  
    queryset = Dashboard.objects.all()
    serializer_class = DashboardSerializer
    authentication_classes = [
        PublicTokenAuthentication,
        PersonalAPIKeyAuthentication,
        authentication.SessionAuthentication,
        authentication.BasicAuthentication,
    ]
    
    permission_classes = []  
    def get_queryset(self) -> QuerySet: