Implement reduce() in terms of append().

api/src/opentrons/protocol_engine/state/update_types.py

@@ -319,19 +319,10 @@ def reduce(cls: typing.Type[Self], *args: Self) -> Self:
         State updates that are later in the parameter list are preferred to those that are earlier;
         NO_CHANGE is ignored.
         """
-        fields = dataclasses.fields(cls)
-        changes_dicts = [
-            {
-                field.name: update.__dict__[field.name]
-                for field in fields
-                if update.__dict__[field.name] != NO_CHANGE
-            }
-            for update in args
-        ]
-        changes = {}
-        for changes_dict in changes_dicts:
-            changes.update(changes_dict)
-        return cls(**changes)
+        accumulator = cls()
+        for arg in args:
+            accumulator.append(arg)
+        return accumulator
 
     # These convenience functions let the caller avoid the boilerplate of constructing a
     # complicated dataclass tree.