Don't hard-code constants in scheduler_dag_execution_timing (#8950)

Slight "improvement" on #8949

scripts/perf/scheduler_dag_execution_timing.py

@@ -131,11 +131,18 @@ def create_dag_runs(dag, num_runs, session):
     from airflow.utils import timezone
     from airflow.utils.state import State
 
+    try:
+        from airflow.utils.types import DagRunType
+        ID_PREFIX = f'{DagRunType.SCHEDULED.value}__'
+    except ImportError:
+        from airflow.models.dagrun import DagRun
+        ID_PREFIX = DagRun.ID_PREFIX
+
     next_run_date = dag.normalize_schedule(dag.start_date or min(t.start_date for t in dag.tasks))
 
     for _ in range(num_runs):
         dag.create_dagrun(
-            run_id="scheduled__" + next_run_date.isoformat(),
+            run_id=ID_PREFIX + next_run_date.isoformat(),
             execution_date=next_run_date,
             start_date=timezone.utcnow(),
             state=State.RUNNING,