[IMP] base: higher priority for vacuum

There are various cases where we observe crons which systematically
face a CPU / memory limit. In a setup where a single worker cron is
launched, a failing cron will prevent subsequent crons to run.

This happens because the limits are evaluated at the worker level: the
worker is killed, then starts over with the same job list order.

If the vacuum cron cannot be run anymore, it leads to tables not
garbage collected anymore (e.g. `bus_bus`), causing performance issues.
To avoid this, we give a higher priority to the vacuum cron.

closes odoo/odoo#144210

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

odoo/addons/base/data/ir_cron_data.xml

@@ -8,6 +8,7 @@
         <field name='interval_number'>1</field>
         <field name='interval_type'>days</field>
         <field name="numbercall">-1</field>
+        <field name="priority">3</field>
     </record>
 
     <record id="ir_cron_res_users_deletion" model="ir.cron">