cmd/cli: doing router setup based on "--iface" flag

Solving downgrading issue from newer version to v1.3.1, and also easier
to explain the logic: either doing "magic stuff" or do nothing.

cmd/cli/main.go

@@ -14,28 +14,26 @@ import (
 )
 
 var (
-	configPath           string
-	configBase64         string
-	daemon               bool
-	listenAddress        string
-	primaryUpstream      string
-	secondaryUpstream    string
-	domains              []string
-	logPath              string
-	homedir              string
-	cacheSize            int
-	cfg                  ctrld.Config
-	verbose              int
-	silent               bool
-	cdUID                string
-	cdOrg                string
-	cdDev                bool
-	iface                string
-	ifaceStartStop       string
-	nextdns              string
-	cdUpstreamProto      string
-	setupRouter          bool
-	setupRouterStartStop bool
+	configPath        string
+	configBase64      string
+	daemon            bool
+	listenAddress     string
+	primaryUpstream   string
+	secondaryUpstream string
+	domains           []string
+	logPath           string
+	homedir           string
+	cacheSize         int
+	cfg               ctrld.Config
+	verbose           int
+	silent            bool
+	cdUID             string
+	cdOrg             string
+	cdDev             bool
+	iface             string
+	ifaceStartStop    string
+	nextdns           string
+	cdUpstreamProto   string
 
 	mainLog       atomic.Pointer[zerolog.Logger]
 	consoleWriter zerolog.ConsoleWriter