[3.12] gh-130250: use support.swap_attr() in test and don't assume we're beginning with a clean system state (GH-130342) (#130345)

gh-130250: use support.swap_attr() in test and don't assume we're beginning with a clean system state (GH-130342)
(cherry picked from commit 048ee2d5ec761296ef67f5c59aee1f24408b12db)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>