[FIX] crm: allow regular salesman to convert and merge opportunities

If an internal user does not belong to Sales / Administrator group, and wants
to convert a lead into an opportunity, he will face an access rights error if
another lead exists with the same email because we are trying to merge them.
We should allow him to convert and merge them without error.

closes odoo/odoo#75283

X-original-commit: 24db93c0e6b88f89fdf03d63afee05fc858ed977
Signed-off-by: Alex Tuyls <alt-odoo@users.noreply.github.com>

addons/crm/wizard/crm_lead_to_opportunity.py

@@ -135,7 +135,7 @@ class Lead2OpportunityPartner(models.TransientModel):
                     'user_id': self.user_id.id,
                     'team_id': self.team_id.id,
                 })
-        (to_merge - result_opportunity).unlink()
+        (to_merge - result_opportunity).sudo().unlink()
         return result_opportunity
 
     def _action_convert(self):