improve fairness of processing_time algorithm

cads_broker/database.py

@@ -440,7 +440,7 @@ def get_users_queue_from_processing_time(
     interval_start = interval_stop - interval
     request_processing_time = sa.sql.func.least(
         SystemRequest.finished_at, interval_stop
-    ) - sa.sql.func.greatest(SystemRequest.started_at, interval_start)
+    ) - SystemRequest.started_at
     user_cumulative_processing_time = sa.sql.func.sum(request_processing_time)
     user_cost = (
         sa.sql.func.extract("epoch", user_cumulative_processing_time)