Refactor logic and improve handling of merge and tracker data

Updated `tracker_payload.source.config` fallback for better reliability, added a `has_data` method in `merge_logic` for clarity, and replaced manual checks with the new method. Additionally, removed obsolete code from the audience joiner to improve maintainability.

Author: atompie

tracardi/service/tracker.py

@@ -36,7 +36,7 @@ def get_bridge(tracker_payload: TrackerPayload) -> Optional[ConfigurableBridge]:
         # TODO GUI should change it in tracker_payload.source. That is why we copy it
 
         if isinstance(tracker_payload.source, EventSource) and isinstance(tracker_payload.source.config, dict):
-            tracker_payload.source.config['static_profile_id'] = tracker_payload.source.permanent_profile_id
+            tracker_payload.source.config['static_profile_id'] = tracker_payload.source.permanent_profile_id or tracker_payload.source.config.get('static_profile_id', False)
 
         if 'webhook' in tracker_payload.source.type:
             return WebHookBridge(