Improvements
- [12144](https://github.com/rasahq/rasa/issues/12144): Add a self-reference of the synonym in the EntitySynonymMapper to handle entities extracted in a casing different to synonym case. (For example if a synonym `austria` is added, entities extracted with any alternate casing of the synonym will also be mapped to `austria`). It addresses ATO-616
Bugfixes
- [12139](https://github.com/rasahq/rasa/issues/12139): Fix 2 issues detected with the HTTP API:
- The `GET /conversations/{conversation_id}/tracker` endpoint was not returning the tracker with all sessions when `include_events` query parameter was set to `ALL`.
The fix constituted in using `TrackerStore.retrieve_full_tracker` method instead of `TrackerStore.retrieve` method in the function handling the `GET /conversations/{conversation_id}/tracker` endpoint.
Implemented or updated this method across all tracker store subclasses.
- The `GET /conversations/{conversation_id}/story` endpoint was not returning all the stories for all sessions when `all_sessions` query parameter was set to `true`.
The fix constituted in using all events of the tracker to be converted in stories instead of only the `applied_events`.
- [12189](https://github.com/rasahq/rasa/issues/12189): Make custom actions inheriting from rasa-sdk `FormValidationAction` parent class an exception of the `selective_domain` rule and always send them domain.