fix: do not count bypassed connections in established counters

[Galoretka]

This change enforces the documented contract that connections matching bypass rules “won’t be counted toward limits.” Previously, while bypassed peers skipped limit checks in handle_established_*, established counters were still incremented unconditionally in on_swarm_event() upon FromSwarm::ConnectionEstablished, causing bypassed connections to inflate total and per-peer counts. This contradicted both the crate-level documentation and the 0.6.0 changelog entry introducing bypass semantics. The fix guards established counter updates behind !is_bypassed(&peer_id), ensuring bypassed connections are neither checked nor counted. Additionally, the per-peer removal path on ConnectionClosed no longer creates empty entries with .or_default() and removes the map entry when empty, preventing stale allocations, which is particularly relevant now that bypassed connections are not inserted into the per-peer map.

[elenaf9]

We already check if a peer is bypassed and early return before checking the per-peer limits:

rust-libp2p/misc/connection-limits/src/lib.rs

Lines 251 to 262 in 0125fa9

	fn handle_established_inbound_connection(
	&mut self,
	connection_id: ConnectionId,
	peer: PeerId,
	_: &Multiaddr,
	_: &Multiaddr,
	) -> Result<THandler<Self>, ConnectionDenied> {
	self.pending_inbound_connections.remove(&connection_id);
	if self.is_bypassed(&peer) {
	return Ok(dummy::ConnectionHandler);
	}

rust-libp2p/misc/connection-limits/src/lib.rs

Lines 307 to 318 in 0125fa9

	fn handle_established_outbound_connection(
	&mut self,
	connection_id: ConnectionId,
	peer: PeerId,
	_: &Multiaddr,
	_: Endpoint,
	_: PortUse,
	) -> Result<THandler<Self>, ConnectionDenied> {
	self.pending_outbound_connections.remove(&connection_id);
	if self.is_bypassed(&peer) {
	return Ok(dummy::ConnectionHandler);
	}

And the total connection count is calculated with established_inbound_connections and established_outbound_connections, not with established_per_peer.