Revert "[FIX] delivery, stock: carrier_id field in incoming stock picking"

This reverts commit 07e6f28df3.

This was no longer possible to create a picking from scratch.
`Inventory > Your Company: Receipts > Create`
Because `picking_type_id` is not in the res returned by the above call to default_get

Even by forcing `picking_type_id` in the `fields` list,
it doesn't return the value in the fields.

addons/delivery/views/delivery_view.xml

@@ -276,7 +276,7 @@
             <field name="arch" type="xml">
                 <xpath expr='//group[@name="carrier_data"]' position='replace'>
                     <group name='carrier_data'>
-                      <field name="carrier_id" attrs="{'invisible': [('picking_type_code', '=', 'incoming')]}"/>
+                      <field name="carrier_id"/>
                       <field name="delivery_type" attrs="{'invisible':True}"/>
                       <label for="carrier_tracking_ref"/>
                       <div>

addons/stock/stock.py

@@ -929,15 +929,6 @@ class stock_picking(models.Model):
         picking_type = self.env['stock.picking.type'].browse(picking_type_id)
         return picking_type.default_location_src_id
 
-    @api.model
-    def default_get(self, fields):
-        res = super(stock_picking, self).default_get(fields)
-        if self._context.get('default_picking_type_id'):
-            picking_type = self.env['stock.picking.type'].browse(res['picking_type_id'])
-            res['picking_type_code'] = picking_type.code
-        return res
-
-
     _columns = {
         'name': fields.char('Reference', select=True, states={'done': [('readonly', True)], 'cancel': [('readonly', True)]}, copy=False),
         'origin': fields.char('Source Document', states={'done': [('readonly', True)], 'cancel': [('readonly', True)]}, help="Reference of the document", select=True),