## 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
if should_refresh(self.context["request"]):
            return insight.team.timezone
        result = get_safe_cache(insight.filters_hash)
        if not result or result.get("task_id", None):
            return None
        return result.get("timezone")
    def get_last_refresh(self, insight: Insight):
        if should_refresh(self.context["request"]):
            return now()
        dashboard_tile = self.dashboard_tile_from_context(insight, self.context.get("dashboard", None))
        result = self.get_result(insight)
        if result is not None:
            if dashboard_tile:
                return dashboard_tile.last_refresh
            else:
                return insight.last_refresh
        if dashboard_tile is not None:
            if dashboard_tile.last_refresh is not None:
                dashboard_tile.last_refresh = None
                dashboard_tile.save(update_fields=["last_refresh"])
        else:
            if insight.last_refresh is not None:
                
                insight.last_refresh = None
                insight.save(update_fields=["last_refresh"])
        return None
    def get_effective_privilege_level(self, insight: Insight) -> Dashboard.PrivilegeLevel: