Run trigger expansion logic only when start_from_trigger is True (#52861)

closes :#52845

Author: vatsrahul1001

airflow-core/src/airflow/models/mappedoperator.py

@@ -62,7 +62,7 @@ def expand_start_from_trigger(self, *, context: Context, session: Session) -> bo
 
         :meta private:
         """
-        if self.partial_kwargs.get("start_from_trigger", self.start_from_trigger):
+        if not self.partial_kwargs.get("start_from_trigger", self.start_from_trigger):
             log.warning(
                 "Starting a mapped task from triggerer is currently unsupported",
                 task_id=self.task_id,