Disallow pending interrupts to be checked during FiberScheduler#unblock #11798

Job	Run time
Windows 11-arm/Visual C++ (btest test-basic test-tool)	17m 26s
Windows 2022/Visual C++ 2022 (check)	26m 28s
Windows 2025/Visual C++ 2022 (test-bundled-gems)	34m 8s
Windows 2025/Visual C++ 2022 (check)	27m 48s
Windows result	2s
	1h 45m 52s

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