Fixed #34346 -- Ordered selected expressions by position.

Used the same approach as for #34176 by using selected expressions
position to prevent ambiguous aliases in collisions.

Thanks henribru for the report.

Regression in 04518e310d.

tests/postgres_tests/test_array.py

@@ -465,10 +465,9 @@ class TestQuerying(PostgreSQLTestCase):
                     {"field__0": 20, "arrayagg": [self.objs[3].pk]},
                 ],
             )
-        alias = connection.ops.quote_name("field__0")
         sql = ctx[0]["sql"]
         self.assertIn("GROUP BY 1", sql)
-        self.assertIn(f"ORDER BY {alias}", sql)
+        self.assertIn("ORDER BY 1", sql)
 
     def test_index(self):
         self.assertSequenceEqual(