transports: Remove `ConnectionError::Timeout` variant

[lexnv]

The ConnectionError::Timeout variant can be deduced from the FailedToNegotiate::SubstreamError.

litep2p/src/transport/tcp/connection.rs

Lines 85 to 106 in c9e7aff

	enum ConnectionError {
	/// Timeout
	Timeout {
	/// Protocol.
	protocol: Option<ProtocolName>,
	/// Substream ID.
	substream_id: Option<SubstreamId>,
	},
	/// Failed to negotiate connection/substream.
	FailedToNegotiate {
	/// Protocol.
	protocol: Option<ProtocolName>,
	/// Substream ID.
	substream_id: Option<SubstreamId>,
	/// Error.
	error: SubstreamError,
	},
	}