chore!(firewall): iptables logger level is set at FIREWALL_IPTABLES_LOG_LEVEL

- firewall log level is still fully controlled by `LOG_LEVEL`
- iptables log level defaults to `info` even if global log level is `debug` to minimize the amount of debug logs
- iptables log level is only set to debug if retro-compatible `FIREWALL_DEBUG=on` or if `FIREWALL_IPTABLES_LOG_LEVEL=debug`

internal/firewall/firewall.go

@@ -34,11 +34,11 @@ type Config struct {
 
 // NewConfig creates a new Config instance and returns an error
 // if no iptables implementation is available.
-func NewConfig(ctx context.Context, logger Logger,
+func NewConfig(ctx context.Context, logger, iptablesLogger Logger,
 	runner CmdRunner, defaultRoutes []routing.DefaultRoute,
 	localNetworks []routing.LocalNetwork,
 ) (config *Config, err error) {
-	impl, err := iptables.New(ctx, runner, logger)
+	impl, err := iptables.New(ctx, runner, iptablesLogger)
 	if err != nil {
 		return nil, fmt.Errorf("creating iptables firewall: %w", err)
 	}