tools: make `v8.nix` more stable #5006

Job	Run time
Build slim tarball	2m 28s
aarch64-linux: with shared libraries	1h 21m 32s
x86_64-linux: with shared libraries	1h 44m 36s
aarch64-darwin: with shared libraries	1h 36m 23s
x86_64-darwin: with shared libraries	2h 33m 4s
	7h 18m 3s

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