## Bug description

From [a customer report](https://posthoghelp.zendesk.com/agent/tickets/653):

```
I'm accessing insight results through the API, and I’ve noticed that sometimes the result is null in the response.
When I go and view the insight in Posthog and tap “refresh” the result starts to return in the API response.
I’ve also noticed there is a “refreshing” boolean flag in the insight response.
How do I set the insight to either refresh periodically or on request so I always get a result through the API?
```

It seems like the insight returns null if it's not refreshed manually from the frontend.

## How to reproduce

1. Call an insight with GET | /api/projects/:project_id/insights/:id
2. Response is `null`
3. Refresh the insight from the frontend
4. Response is populated

## Environment

- [ ] PostHog Cloud
- [ ] self-hosted PostHog, version/commit: please provide

## Additional context


posthog/api/insight.py
team = self.team
        filter = Filter(request=request, team=self.team)
        if filter.insight == INSIGHT_STICKINESS or filter.shown_as == TRENDS_STICKINESS:
            stickiness_filter = StickinessFilter(
                request=request, team=team, get_earliest_timestamp=get_earliest_timestamp
            )
            result = self.stickiness_query_class().run(stickiness_filter, team)
        else:
            trends_query = Trends()
            result = trends_query.run(filter, team)
        return {"result": result, "timezone": team.timezone}
    
    
    
    
    #
    
    
    
    
    
    @extend_schema(
        request=FunnelSerializer,
        responses=OpenApiResponse(
            response=FunnelStepsResultsSerializer,
            description="Note, if funnel_viz_type is set the response will be different.",
        ),
        methods=["POST"],
        tags=["funnel"],
        operation_id="Funnels",