[3.11] gh-109840: Fix multiprocessing test_waitfor_timeout() (GH-110428) (#110431)

gh-109840: Fix multiprocessing test_waitfor_timeout() (GH-110428)

Don't measure the CI performance: don't fail if cond.wait_for() takes
longer than 1 second on a slow CI.
(cherry picked from commit 5eae8dc2cb832af6ae1ee340fb0194107fe3bd6e)

Co-authored-by: Victor Stinner <vstinner@python.org>