[FIX] event: restrict event_count field on partner for event user only

Currently event_count is a computed field with a shortcut in computation for
non event user. It is better to directly limit this field to the event_user
group instead.

LINKS

Side effect of Task ID 2089156 (event onchange to compute)
Community PR odoo/odoo#43127
Enterprise PR odoo/enterprise#7656

addons/event/models/res_partner.py

@@ -3,10 +3,13 @@
 
 from odoo import api, fields, models
 
+
 class ResPartner(models.Model):
     _inherit = 'res.partner'
 
-    event_count = fields.Integer("Events", compute='_compute_event_count', help="Number of events the partner has participated.")
+    event_count = fields.Integer(
+        '# Events', compute='_compute_event_count', groups='event.group_event_user',
+        help='Number of events the partner has participated.')
 
     def _compute_event_count(self):
         self.event_count = 0