Get rid of `libp2p` dependency in `sc-authority-discovery` #13328

Job	Run time
check-dependency-rules	10s
check-fail-ci	12s
check-markdown	15s
check-workspace	19s
preflight / preflight	45s
preflight / ci-versions	59s
test-rust-features	2m 7s
check-rust-feature-propagation	2m 5s
check-toml-format	57s
fmt	1m 4s
check-umbrella	2m 23s
All quick checks passed	1s
	11m 17s

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