Add @disjoint_base decorator in the stdlib (#14599)

And fix some other new stubtest finds.

stdlib/sre_constants.pyi

@@ -1,15 +1,22 @@
 import sys
 from re import error as error
 from typing import Final
-from typing_extensions import Self
+from typing_extensions import Self, disjoint_base
 
 MAXGROUPS: Final[int]
 
 MAGIC: Final[int]
 
-class _NamedIntConstant(int):
-    name: str
-    def __new__(cls, value: int, name: str) -> Self: ...
+if sys.version_info >= (3, 12):
+    class _NamedIntConstant(int):
+        name: str
+        def __new__(cls, value: int, name: str) -> Self: ...
+
+else:
+    @disjoint_base
+    class _NamedIntConstant(int):
+        name: str
+        def __new__(cls, value: int, name: str) -> Self: ...
 
 MAXREPEAT: Final[_NamedIntConstant]
 OPCODES: list[_NamedIntConstant]