trigger_resource.go: after CreateTrigger, if URL is empty (HTTP trigger), retry GetTrigger every 2s up to 30s until controller sets status.URL. Without this, URL in terraform state was always empty after apply.
trigger_resource.go: after CreateTrigger, if URL is empty (HTTP trigger), retry GetTrigger every 2s up to 30s until controller sets status.URL. Without this, URL in terraform state was always empty after apply.