[FIX] ir.cron: execute jobs in priority order (again)

The selection mechanism selects 1 job at a time from the jobs that are
ready to execute, but while doing this it should respect the `priority`
defined on the jobs. Otherwise the field is useless, and the user has no
way to ensure that a long-running job does not cause starvation.
(Assuming execution resources that are insufficient for 100% of the
processing to happen)

The `priority` ordering was apparently lost during the introduction of
the trigger mechanism in #62124 via
4b28f1162a.
It was previously taken into account in `_process_jobs()`.

The `ORDER BY` is not strictly necessary in `_get_all_ready_jobs()`, but
it seems more consistent for this method to return an ordered list as
well, given the semantics of the `priority` field. We don't know what
the caller will do with the result.

closes odoo/odoo#68411

X-original-commit: 9d570662b4016b5cd9ad3c85abbcb5428c169cc6
Signed-off-by: Olivier Dony (odo) <odo@openerp.com>

odoo/addons/base/models/ir_cron.py

@@ -179,6 +179,7 @@ class ir_cron(models.Model):
                     WHERE call_at <= (now() at time zone 'UTC')
                 )
               )
+            ORDER BY priority
         """)
         return cr.dictfetchall()
 
@@ -224,6 +225,7 @@ class ir_cron(models.Model):
                 )
               )
               AND id in %s
+            ORDER BY priority
             LIMIT 1 FOR NO KEY UPDATE SKIP LOCKED
         """, [job_ids])
         return cr.dictfetchone()