refactor: witness caching skips the 1st witness. #2416

Job	Run time
linux	14m 20s
code-quality / lints	6m 2s
licenses-audits / cargo-deny (advisories, licenses, bans, ...)	48s
link-checker / linkChecker	7s
msrv / msrv	4m 27s
wasm / wasm-build	2m 49s
	28m 33s

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