Don't allow registration via the web form, when AllowOnlyExternalRegistration is True (#11248)

* Don't allow registration via the web form, when AllowOnlyExternalRegistration is True

* Show Disabled Registration message if DisableRegistration or AllowOnlyExternalRegistration options are true

routers/user/auth.go

@@ -1021,7 +1021,8 @@ func SignUp(ctx *context.Context) {
 	ctx.Data["CaptchaType"] = setting.Service.CaptchaType
 	ctx.Data["RecaptchaSitekey"] = setting.Service.RecaptchaSitekey
 
-	ctx.Data["DisableRegistration"] = setting.Service.DisableRegistration
+	//Show Disabled Registration message if DisableRegistration or AllowOnlyExternalRegistration options are true
+	ctx.Data["DisableRegistration"] = setting.Service.DisableRegistration || setting.Service.AllowOnlyExternalRegistration
 
 	ctx.HTML(200, tplSignUp)
 }
@@ -1038,7 +1039,7 @@ func SignUpPost(ctx *context.Context, cpt *captcha.Captcha, form auth.RegisterFo
 	ctx.Data["RecaptchaSitekey"] = setting.Service.RecaptchaSitekey
 
 	//Permission denied if DisableRegistration or AllowOnlyExternalRegistration options are true
-	if setting.Service.DisableRegistration {
+	if setting.Service.DisableRegistration || setting.Service.AllowOnlyExternalRegistration {
 		ctx.Error(403)
 		return
 	}