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/iptables/interfaces.go

@@ -8,7 +8,5 @@ type CmdRunner interface {
 
 type Logger interface {
 	Debug(s string)
-	Info(s string)
 	Warn(s string)
-	Error(s string)
 }