[FIX] mail: use current user company in notification

When sending a notification, the company used is:

- company_id of current record or if not available,
- company_id of author or if no author,
- company_id of user

This can seem unexpected if the author is the current user and the
company_id of our user is different than the current company switcher
company.

With this changeset: the company used is:

- company_id of current record or if not available,
- company_id of author if author is different than user or,
- current company in company switcher or if not,
- company_id of user

opw-2472622

closes odoo/odoo#73031

X-original-commit: 3f61d9e2dadf47d211ed078b36e9f3a416bbbff0
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>

addons/mail/models/mail_thread.py

@@ -2326,7 +2326,9 @@ class MailThread(models.AbstractModel):
             if add_sign:
                 signature = "<p>-- <br/>%s</p>" % author.name
 
-        company = self.company_id.sudo() if self and 'company_id' in self else user.company_id
+        # use company switcher company if author is current user
+        user_company = self.env.company if self.env.user == user else user.company_id
+        company = self.company_id.sudo() if self and 'company_id' in self else user_company
         if company.website:
             website_url = 'http://%s' % company.website if not company.website.lower().startswith(('http:', 'https:')) else company.website
         else: