[3.12] gh-122792: Make IPv4-mapped IPv6 address properties consistent with IPv4 (GH-122793) (GH-123814)

gh-122792: Make IPv4-mapped IPv6 address properties consistent with IPv4 (GH-122793)

Make IPv4-mapped IPv6 address properties consistent with IPv4.
(cherry picked from commit 76a1c5d18312712baed4699fe7333abb050ec9b7)

Co-authored-by: Seth Michael Larson <seth@python.org>