## Issue
https://github.com/paritytech/polkadot-sdk/issues/4858

## Description
This PR removes `libp2p::request_response::OutboundFailure` from
`substrate/client/network/sync/src/engine.rs`. This way, the dependency
with the library `libp2p` is removed from `sc-network-sync`.

---------

Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: command-bot <>
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>