Instead of using libp2p-provided external address candidates,
susceptible to address translation issues, use litep2p-backend approach
based on confirming addresses observed by multiple peers as external.

Fixes https://github.com/paritytech/polkadot-sdk/issues/7207.

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Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>