use a single place to define xxd clean #239

Job	Run time
macos (tiny, macos-13)	1m 15s
windows (HUGE, msvc, no, no, x64, stable)	5m 56s
macos (tiny, macos-14)	56s
linux (tiny, clang, native)	2m 12s
windows (HUGE, mingw, yes, yes, x86, stable, yes)	9m 52s
macos (normal, macos-13)	6m 12s
linux (tiny, gcc, native)	2m 17s
windows (HUGE, msvc, no, yes, x86)	8m 45s
macos (normal, macos-14)	5m 8s
linux (normal, clang, native)	5m 24s
windows (HUGE, mingw, yes, no, x64, yes)	9m 43s
macos (huge, macos-13)	20m 14s
linux (normal, gcc, native)	5m 14s
macos (huge, macos-14)	17m 38s
windows (NORMAL, msvc, yes, no, x86)	6m 42s
linux (huge, clang, native)	11m 13s
windows (NORMAL, mingw, no, yes, x64)	8m 56s
linux (huge, gcc, native)	13m 27s
windows (TINY, msvc, yes, yes, x64)	1m 29s
linux (tiny, clang, nogui)	1m 42s
windows (TINY, mingw, no, no, x86)	2m 38s
linux (tiny, gcc, nogui)	2m 4s
linux (normal, gcc, i386, ./src/shadow)	6m 5s
linux (huge, gcc, uchar, testgui, true, dynamic)	10m 25s
linux (huge, clang, asan, 5.1)	24m 22s
linux (huge, gcc, unittests, true)	2m 49s
linux (normal, gcc, vimtags)	2m 9s
	3h 14m 47s

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