doc,test: remove usage of util.inherits #1072

Job	Run time
Build slim tarball	1m 37s
aarch64-linux: with shared libraries	24m 24s
x86_64-linux: with shared libraries	29m 7s
x86_64-darwin: with shared libraries	50m 25s
aarch64-darwin: with shared libraries	27m 9s
	2h 12m 42s

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