[FIX] mass_mailing: disable A/B testing cron by default

Before this commit, the A/B testing cron was active by default.
It doesn't matter if A/B testing is true or false in settings.
So, with this commit, we set active equals to false by default
in the A/B testing cron. It will be active when the user sets
`group_mass_mailing_campaign` to True.

TaskId-2713198

X-original-commit: b348f8658f87c15d0fe4ee72888e99da2a529700
Part-of: odoo/odoo#107488

addons/mass_mailing/data/ir_cron_data.xml

@@ -20,6 +20,7 @@
             <field name="state">code</field>
             <field name="code">model._cron_process_mass_mailing_ab_testing()</field>
             <field name="user_id" ref="base.user_root"/>
+            <field name="active" eval="False"/>
             <field name="interval_number">1</field>
             <field name="interval_type">days</field>
             <field name="numbercall">-1</field>