[batch] Do not lock when querying billing projects (#14443)

Decided to tackle this as it was causing noise in the logs. There is no
reason this read-only select query should lock any rows.

Author: daniel-goldstein

batch/batch/utils.py

@@ -157,8 +157,7 @@ async def query_billing_projects_with_cost(db, user=None, billing_project=None)
   ) AS usage_t
   LEFT JOIN resources ON resources.resource_id = usage_t.resource_id
 ) AS cost_t ON TRUE
-{where_condition}
-LOCK IN SHARE MODE;
+{where_condition};
 """
 
     billing_projects = []