gc: change some atomic memory orderings #12818

Job	Run time
Windows 2025/Visual C++ 2022 (test-bundled-gems)	31m 40s
Windows 2025/Visual C++ 2022 (check)	30m 37s
Windows 2022/Visual C++ 2022 (check)	25m 44s
Windows 11-arm/Visual C++ (btest test-basic test-tool)	45m 13s
Windows result	2s
	2h 13m 16s

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