Update the ordering in query for ActiveRecordWithLock adapter

why?
This is to test the performance of the query for databse that uses
lsm and SST for storage. When the load is huge there is pperformance
degredation because of the dead tuples building up. we want move job_id
before run_at.

lib/que/sql.rb

@@ -183,7 +183,7 @@ module Que
             AND run_at <= now()
             AND retryable = true
             AND job_id >= $2
-            ORDER BY priority, run_at, job_id
+            ORDER BY priority, job_id, run_at
             FOR UPDATE SKIP LOCKED
             LIMIT 1
     },