[v3-1-test] fix flaky TestEmrCreateJobFlowOperator (#59128) (#59137)

(cherry picked from commit 97cf3c7)

Co-authored-by: Henry Chen <[email protected]>

Author: 2 people

devel-common/src/tests_common/test_utils/db.py

@@ -252,9 +252,9 @@ def clear_db_dags():
             session.query(DagFavorite).delete()
         session.query(DagTag).delete()
         session.query(DagOwnerAttributes).delete()
-        session.query(
-            DagRun
-        ).delete()  # todo: this should not be necessary because the fk to DagVersion should be ON DELETE SET NULL
+        session.query(DagRun).delete(
+            synchronize_session=False
+        )  # todo: this should not be necessary because the fk to DagVersion should be ON DELETE SET NULL
         session.query(DagModel).delete()