[Doppel]: Migrate Doppel to GA

## Integration GA Checklist

### All changes

- [x] Change follows the [contributing guidelines](https://github.com/elastic/integrations/blob/main/CONTRIBUTING.md)
- [x] Supported versions of the monitoring target are documented
- [ ] ~Supported operating systems are documented (if applicable)~
- [x] Integration or [System tests](https://github.com/elastic/elastic-package/blob/master/docs/howto/system_testing.md) exist
- [x] Documentation exists, [useful guidelines](https://github.com/elastic/integrations/blob/main/docs/documentation_guidelines.md) to follow
- [x] Fields follow [ECS](https://github.com/elastic/ecs) and [naming conventions](https://www.elastic.co/guide/en/beats/devguide/master/event-conventions.html)
- [x] At least a manual test with ES / Kibana / Agent has been performed.
- [x] Required Kibana version set to: "^8.19.14 || ^9.3.3"
- [x] Dashboards exists
- [x] Screenshots added or updated
- [ ] Datastream filters added to visualizations
- [x] Sample event (`sample_event.json`) exists
- [x] Existing issue closed https://github.com/elastic/integrations/issues?q=is%3Aissue%20state%3Aopen%20label%3Adoppel
- [x] Agentless if can be supported