gh-114096: Restore privileges in _winapi.CreateJunction after creating the junction (GH-114089)

This avoids impact on later parts of the application which may be able to do things they otherwise shouldn't.
(cherry picked from commit de4ced54eb08e8630e3b6c13436d4ecc3fb14708)

Co-authored-by: Steve Dower <steve.dower@python.org>