stdlib: add a few more defaults (#14618)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

stdlib/lib2to3/fixes/fix_tuple_params.pyi

@@ -1,4 +1,3 @@
-from _typeshed import Incomplete
 from typing import ClassVar, Literal
 
 from .. import fixer_base
@@ -13,5 +12,5 @@ class FixTupleParams(fixer_base.BaseFix):
 
 def simplify_args(node): ...
 def find_params(node): ...
-def map_to_index(param_list, prefix=..., d: Incomplete | None = ...): ...
+def map_to_index(param_list, prefix=[], d=None): ...
 def tuple_name(param_list): ...