tools: make `v8.nix` more stable #5245

Job	Run time
Build slim tarball	2m 0s
aarch64-linux: with shared libraries	1h 19m 24s
x86_64-darwin: with shared libraries	2h 10m 12s
x86_64-linux: with shared libraries	1h 43m 45s
aarch64-darwin: with shared libraries	2h 18m 35s
	7h 33m 56s

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