[Alerting]: Fix YAML encoding/decoding issues when proxying lotex requests (#32854)

* [Alerting]: Fix GET lotex rule group config

* [Alerting]: Fix POST lotex user config

pkg/services/ngalert/api/lotex_am.go

@@ -147,7 +147,7 @@ func (am *LotexAM) RouteGetSilences(ctx *models.ReqContext) response.Response {
 }
 
 func (am *LotexAM) RoutePostAlertingConfig(ctx *models.ReqContext, config apimodels.PostableUserConfig) response.Response {
-	yml, err := yaml.Marshal(config)
+	yml, err := yaml.Marshal(&config)
 	if err != nil {
 		return response.Error(500, "Failed marshal alert manager configuration ", err)
 	}

pkg/services/ngalert/api/lotex_ruler.go

@@ -112,7 +112,7 @@ func (r *LotexRuler) RouteGetRulegGroupConfig(ctx *models.ReqContext) response.R
 			),
 		),
 		nil,
-		yamlExtractor(apimodels.RuleGroupConfigResponse{}),
+		yamlExtractor(&apimodels.GettableRuleGroupConfig{}),
 		nil,
 	)
 }