[IMP] base: do not format email for partners not having email

Currently if a partner has a void email, its email_formatted field holds
a value like "Raoul Grosbedon <False>" which is quite rarely considered
as a valid email address.

Minimal fix for this field is to return a void value if there is no email.
Having a void return is easier to manipulate for callers in order to
handle it.

This commit is linked to task ID 1860049 and PR #25824.

odoo/addons/base/models/res_partner.py

@@ -374,7 +374,10 @@ class Partner(models.Model):
     @api.depends('name', 'email')
     def _compute_email_formatted(self):
         for partner in self:
-            partner.email_formatted = formataddr((partner.name or u"False", partner.email or u"False"))
+            if partner.email:
+                partner.email_formatted = formataddr((partner.name or u"False", partner.email or u"False"))
+            else:
+                partner.email_formatted = ''
 
     @api.depends('is_company')
     def _compute_company_type(self):