Fix test_faulthandler on UBSan

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Bug report

Currently, running test_faulthandler on UBSan logs multiple errors. Errors are logged by subprocesses run by the test.

I'm working on fixing these errors.

Linked PRs

• gh-151278: Fix test_faulthandler on UBSan #151279
• [3.15] gh-151278: Fix test_faulthandler on UBSan (GH-151279) #151281
• [3.14] gh-151278: Fix test_faulthandler on UBSan (#151279) #151282

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See also #151274 (comment) for test_capi failure.

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I created #151284 for test_capi.

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I didn't backport the fix to 3.13 since Python raises too many UBSan errors in 3.13.