Revert "Go from 2 to 1 allocations in onig_region_resize" #12898

Job	Run time
Windows 2022/Visual C++ 2022 (check)	4m 12s
Windows 2025/Visual C++ 2022 (check)	5m 2s
Windows 11-arm/Visual C++ (btest test-basic test-tool)	6m 19s
Windows 2025/Visual C++ 2022 (test-bundled-gems)	4m 30s
Windows result	18s
	20m 21s

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