test_multiprocessing_spawn leaked a temporary file (`tmpx_v21ney`) on FreeBSD 16

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AMD64 FreeBSD16 3.x: https://buildbot.python.org/#/builders/1857/builds/882

0:08:06 load avg: 3.91 mem: 389.2 MiB [252/558/1] test.test_multiprocessing_spawn.test_manager failed (env changed) (41.8 sec) -- running (1): test.test_multiprocessing_forkserver.test_processes (56.5 sec)
test_abort (test.test_multiprocessing_spawn.test_manager.WithManagerTestBarrier.test_abort)
Test that an abort will put the barrier in a broken state ... ok
test_abort_and_reset (test.test_multiprocessing_spawn.test_manager.WithManagerTestBarrier.test_abort_and_reset)
Test that a barrier can be reset after being broken. ... ok
(...)

Ran 91 tests in 40.644s

OK (skipped=19)

Warning -- test.test_multiprocessing_spawn.test_manager leaked temporary files (1): tmpx_v21ney

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Another example on GHA Ubuntu (free-threading) / build and test (ubuntu-26.04): https://github.com/python/cpython/actions/runs/37567653961/job/112619464442?pr=158951

Warning -- test_multiprocessing_main_handling leaked temporary files (1): tmpnem91ie0

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Or on AMD64 FreeBSD15 3.x: https://buildbot.python.org/#/builders/1238/builds/10065

Warning -- test.test_multiprocessing_spawn.test_processes leaked temporary files (1): tmptge2pc94

and

Warning -- test_multiprocessing_main_handling leaked temporary files (1): tmphd6ce4af