[FIX] base: make check_credentials more consistent with alternatives

The other methods do test password length before verifying it, so even
if check_credentials() is not meant to be called directly, it's better
to keep it consistent with the alternatives.

Closes #29023

odoo/addons/base/res/res_users.py

@@ -444,6 +444,8 @@ class Users(models.Model):
     @api.model
     def check_credentials(self, password):
         """ Override this method to plug additional authentication methods"""
+        if not password:
+            raise AccessDenied()
         user = self.sudo().search([('id', '=', self._uid), ('password', '=', password)])
         if not user:
             raise AccessDenied()