Don't expose metadata for Runtime APIs that haven't been implemented #12929

Job	Run time
check-markdown	15s
check-dependency-rules	11s
check-workspace	26s
check-fail-ci	12s
preflight / preflight	43s
preflight / ci-versions	1m 4s
check-rust-feature-propagation	2m 4s
check-toml-format	59s
check-umbrella	2m 25s
fmt	1m 8s
test-rust-features	2m 4s
All quick checks passed	1s
	11m 32s

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