[FIX] rma: default team and responsible

Having a default responsible value as it was defined doesn't behave
right when the user it's a portal one or the petition comes from a
sudo().

Also, by design it was expected to have a default team if it wasn't
defined, but as it was implemented that wasn't possible.

TT32056

rma/models/rma.py

@@ -50,7 +50,6 @@ class Rma(models.Model):
         comodel_name="res.users",
         string="Responsible",
         index=True,
-        default=lambda self: self.env.user,
         tracking=True,
         states={"locked": [("readonly", True)], "cancelled": [("readonly", True)]},
     )
@@ -509,7 +508,7 @@ class Rma(models.Model):
                     ir_sequence = ir_sequence.with_company(vals["company_id"])
                 vals["name"] = ir_sequence.next_by_code("rma")
             # Assign a default team_id which will be the first in the sequence
-            if "team_id" not in vals:
+            if not vals.get("team_id"):
                 vals["team_id"] = self.env["rma.team"].search([], limit=1).id
         rmas = super().create(vals_list)
         # Send acknowledge when the RMA is created from the portal and the