[3.12] gh-88118: Fix some test_multiprocessing flakiness. (GH-116434) #105252

Job	Run time
Check for source changes	8s
Check if generated files are up to date	5m 28s
Check if the ABI has changed	1m 29s
Address sanitizer	7m 19s
Ubuntu SSL tests with OpenSSL (1.1.1w)	2m 41s
Docs	0s
Ubuntu SSL tests with OpenSSL (3.0.13)	3m 18s
Hypothesis tests on Ubuntu	4m 38s
Ubuntu SSL tests with OpenSSL (3.1.5)	2m 54s
Ubuntu SSL tests with OpenSSL (3.2.1)	2m 55s
macOS / build and test (macos-14)	8m 9s
macOS / build and test (macos-13)	11m 45s
Ubuntu / build and test	8m 10s
Windows / build and test (x64)	14m 18s
Windows / build (arm64)	3m 21s
Windows / build and test (x86)	14m 5s
All required checks pass	4s
	1h 30m 42s

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