transport/manager: Investigate connection closed for a nonexistent peer

[lexnv]

Substrate panic triggered on debug_assert:

Thread 'tokio-runtime-worker' panicked at 'assertion failed: false', /usr/local/cargo/registry/src/index.crates.io-6f17d22bba15001f/litep2p-0.6.2/src/protocol/transport_service.rs:220

Code path:

litep2p/src/protocol/transport_service.rs

Lines 212 to 222 in a27d007

	let Some(context) = self.connections.get_mut(&peer) else {
	tracing::warn!(
	target: LOG_TARGET,
	?peer,
	?connection_id,
	"connection closed to a non-existent peer",
	);
	debug_assert!(false);
	return None;
	};

Substrate issue: paritytech/polkadot-sdk#5595
Grafana link: https://grafana.teleport.parity.io/goto/sR83XkeSg?orgId=1