[IMP] various: prevent unlink of automated activity types

Purpose of this merge is to update main addons and set activity types used
for automated activities as master data. This means they cannot be removed.
Indeed those activity types are used in business flow to generate activities
and removing them may break some flows.

This commit is linked to task ID 1907970 and PR #29257.

addons/maintenance/data/mail_data.xml

@@ -6,6 +6,7 @@
         <field name="name">Maintenance Request</field>
         <field name="icon">fa-wrench</field>
         <field name="res_model_id" ref="maintenance.model_maintenance_request"/>
+        <field name="is_master_data">True</field>
     </record>
 
     <!-- email alias for maintenance requests -->