[FIX] mail: set default _rec_name to avoid showing model with id

closes odoo/odoo#27186

addons/mail/models/mail_tracking_value.py

@@ -9,6 +9,7 @@ from odoo import api, fields, models, tools
 class MailTracking(models.Model):
     _name = 'mail.tracking.value'
     _description = 'Mail Tracking Value'
+    _rec_name = 'field'
 
     # TDE CLEANME: why not a m2o to ir model field ?
     field = fields.Char('Changed Field', required=True, readonly=1)