[3.12] gh-109702: Increase concurrent_futures deadlock timeout (GH-109703) (#109705)

gh-109702: Increase concurrent_futures deadlock timeout (GH-109703)

Replace SHORT_TIMEOUT with LONG_TIMEOUT in test_deadlock of
test_concurrent_futures.
(cherry picked from commit 1eb1b45183c3b8aeefe3d5d27694155741e82bbc)

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