[IMP] mail: add default values when creating template from server action

Better avoid wrongly-defined templates.

Task-2613245 (Server actions mail update / cleaning)

Part-of: odoo/odoo#75906

addons/mail/views/ir_actions_server_views.xml

@@ -11,7 +11,8 @@
                     <page string="Activity" name="next_activity" autofocus="autofocus" attrs="{'invisible': [('state', '!=', 'next_activity')]}">
                         <group>
                             <group>
-                                <field name="activity_type_id" options="{'no_create': True, 'no_open': True}" attrs="{'required': [('state', '=', 'next_activity')]}"/>
+                                <field name="activity_type_id" options="{'no_create': True, 'no_open': True}"
+                                       attrs="{'required': [('state', '=', 'next_activity')]}"/>
                                 <field name="activity_summary" placeholder="e.g. Discuss proposal"/>
                             </group>
                             <group>
@@ -43,7 +44,9 @@
                            attrs="{'invisible': [('state', '!=', 'followers')]}"/>
                     <field name="template_id"
                            attrs="{'invisible': [('state', '!=', 'mail_post')],
-                                   'required': [('state', '=', 'mail_post')]}"/>
+                                   'required': [('state', '=', 'mail_post')]}"
+                           context="{'default_model': model_name,
+                                     'default_use_default_to': True}"/>
                     <field name="mail_post_method"
                            attrs="{'invisible': [('state', '!=', 'mail_post')],
                                    'required': [('state', '=', 'mail_post')]}"/>