Add @type_check_only to various typeshed-only procotols in stdlib (#14465)

Mark various typeshed-only protocols as `@type_check_only` in stdlib

stdlib/gettext.pyi

@@ -2,7 +2,7 @@ import io
 import sys
 from _typeshed import StrPath
 from collections.abc import Callable, Container, Iterable, Sequence
-from typing import Any, Final, Literal, Protocol, TypeVar, overload
+from typing import Any, Final, Literal, Protocol, TypeVar, overload, type_check_only
 
 __all__ = [
     "NullTranslations",
@@ -26,6 +26,7 @@ __all__ = [
 if sys.version_info < (3, 11):
     __all__ += ["bind_textdomain_codeset", "ldgettext", "ldngettext", "lgettext", "lngettext"]
 
+@type_check_only
 class _TranslationsReader(Protocol):
     def read(self) -> bytes: ...
     # optional: