VTK: Remove unused cstdlib include and clarify NaN bounds safety #23085

Job	Run time
build (Release, Windows Latest MSVC, windows-2022, cl, cl, true, true, true, true, false, bootstr...	13m 54s
build (Release, Ubuntu 24.04 clang-19, ubuntu-24.04, clang-19, clang++-19, true, true, false, fal...	8m 1s
build (Release, Ubuntu 24.04 gcc, ubuntu-24.04, gcc-14, g++-14, true, true, true, false, true, bo...	8m 48s
build (Release, Windows_2022_qt_610, windows-2022, cl, cl, false, true, false, true, false, boots...	10m 44s
Upload release to PyPI	0s
	41m 27s

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