[FIX] website: prevent SQL deadlock with website.visitor

Since it's first implementation at [1], a new cursor is created to then
build a new environment after the website's `authenticate` overide with
the new `uid` of the logged in user.

Since the new visitor SQL upsert refactoring done at [2], it seems to be
introducing a SQL deadlock sometimes.
It has been detected on odoo.com while monitoring the logs. Despite
being quite rare, it still happens too often due to our heavy trafic.

Step to reproduce (among others):
- Install website_livechat
- Login as admin on 127.0.0.1
- On 127.0.0.2, load the website
- Open the livechat
- Type something in the discussion
- Directly try to login as admin
- It will load for a certain time then crash on a 502 timeout due to the
  SQL deadlock
- You may need to repeat the process to actually face the bug

[1]: odoo@6bec0e4
[2]: odoo@d348bed

closes odoo#109746

Signed-off-by: Olivier Dony (odo) <[email protected]>

addons/website/models/res_users.py

@@ -72,19 +72,18 @@ def authenticate(cls, db, login, password, user_agent_env):
             visitor_pre_authenticate_sudo = request.env['website.visitor']._get_visitor_from_request()
         uid = super(ResUsers, cls).authenticate(db, login, password, user_agent_env)
         if uid and visitor_pre_authenticate_sudo:
-            with cls.pool.cursor() as cr:
-                env = api.Environment(cr, uid, {})
-                user_partner = env.user.partner_id
-                visitor_current_user_sudo = env['website.visitor'].sudo().search([
-                    ('partner_id', '=', user_partner.id)
-                ], limit=1)
-                if visitor_current_user_sudo:
-                    # A visitor exists for the logged in user, link public
-                    # visitor records to it.
-                    if visitor_pre_authenticate_sudo != visitor_current_user_sudo:
-                        visitor_pre_authenticate_sudo._merge_visitor(visitor_current_user_sudo)
-                    visitor_current_user_sudo._update_visitor_last_visit()
-                else:
-                    visitor_pre_authenticate_sudo.access_token = user_partner.id
-                    visitor_pre_authenticate_sudo._update_visitor_last_visit()
+            env = api.Environment(request.env.cr, uid, {})
+            user_partner = env.user.partner_id
+            visitor_current_user_sudo = env['website.visitor'].sudo().search([
+                ('partner_id', '=', user_partner.id)
+            ], limit=1)
+            if visitor_current_user_sudo:
+                # A visitor exists for the logged in user, link public
+                # visitor records to it.
+                if visitor_pre_authenticate_sudo != visitor_current_user_sudo:
+                    visitor_pre_authenticate_sudo._merge_visitor(visitor_current_user_sudo)
+                visitor_current_user_sudo._update_visitor_last_visit()
+            else:
+                visitor_pre_authenticate_sudo.access_token = user_partner.id
+                visitor_pre_authenticate_sudo._update_visitor_last_visit()
         return uid