Hide nonce implementation details in metadata #14642

Job	Run time
check-dependency-rules	11s
check-fail-ci	17s
check-markdown	19s
check-readme	3m 5s
check-workspace	19s
preflight / preflight	43s
preflight / ci-versions	1m 31s
check-rust-feature-propagation	2m 31s
test-rust-features	2m 23s
check-toml-format	1m 12s
check-umbrella	2m 35s
fmt	1m 20s
All quick checks passed	1s
	16m 27s

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