fix(dashboard): Generate screenshot via celery (#32193)

Co-authored-by: Erkka Tahvanainen <[email protected]>

Author: tahvane1

superset/dashboards/api.py

@@ -1130,6 +1130,7 @@ def build_response(status_code: int) -> WerkzeugResponse:
                 dashboard_id=dashboard.id,
                 dashboard_url=dashboard_url,
                 thumb_size=thumb_size,
+                cache_key=cache_key,
                 window_size=window_size,
                 cache_key=cache_key,
                 force=force,