Avoid redundant SET conversion (#11091)

* Avoid redundant SET conversion

get_accessible_dag_ids() returns a SET, so no need to apply set() again

* Add type annotation for get_accessible_dag_ids()

airflow/www/security.py

@@ -17,6 +17,8 @@
 # under the License.
 #
 
+from typing import Set
+
 from flask import current_app, g
 from flask_appbuilder.security.sqla import models as sqla_models
 from flask_appbuilder.security.sqla.manager import SecurityManager
@@ -307,7 +309,7 @@ class AirflowSecurityManager(SecurityManager, LoggingMixin):
 
         return session.query(DagModel).filter(DagModel.dag_id.in_(resources))
 
-    def get_accessible_dag_ids(self, username=None):
+    def get_accessible_dag_ids(self, username=None) -> Set[str]:
         """
         Return a set of dags that user has access to(either read or write).
 

airflow/www/views.py

@@ -588,7 +588,7 @@ class Airflow(AirflowBaseView):  # noqa: D101  pylint: disable=too-many-public-m
     @provide_session
     def task_stats(self, session=None):
         """Task Statistics"""
-        allowed_dag_ids = set(current_app.appbuilder.sm.get_accessible_dag_ids())
+        allowed_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
 
         if not allowed_dag_ids:
             return wwwutils.json_response({})