fix(airflow.cfg): fix duplicate core.max_active_tasks_per_dag

Author: Lee-W

airflow.cfg

@@ -5,7 +5,7 @@
 parallelism = 4
 
 # The number of task instances allowed to run concurrently by the scheduler
-max_active_tasks_per_dag = 64
+max_active_tasks_per_dag = 2
 
 # Whether to load the examples that ship with Airflow. It's good to
 # get started, but you probably want to set this to False in a production
@@ -21,7 +21,6 @@ dagbag_import_timeout = 600
 auth_manager = airflow.providers.fab.auth_manager.fab_auth_manager.FabAuthManager
 
 max_active_runs_per_dag = 2
-max_active_tasks_per_dag = 2
 
 [dag_processor]
 # How long before timing out a DagFileProcessor, which processes a dag file