Singleton classes of unshareable objects are not shareable #12525

Job	Run time
Windows 2025/Visual C++ 2022 (test-bundled-gems)	20m 25s
Windows 2025/Visual C++ 2022 (check)	23m 41s
Windows 11-arm/Visual C++ (btest test-basic test-tool)	18m 58s
Windows 2022/Visual C++ 2022 (check)	13m 2s
Windows result	4s
	1h 16m 10s

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