fix: 完善多云同步验证与实例统计

- 修复华为云签名、账单字段与区域映射缓存
- 按真实云实例更新账号服务器数并补充并发测试

backend/controller/cloud_accounts.go

@@ -33,24 +33,6 @@ func NewCloudAccountHandler(db *gorm.DB) *CloudAccountHandler {
 func (h *CloudAccountHandler) ListCloudAccounts(c *gin.Context) {
 	var accounts []model.CloudAccount
 	h.db.Find(&accounts)
-	// 服务器数来自真实云账号关联，避免重复导入后被“本次新增数”覆盖。 // Logan.Li
-	type accountServerCount struct {
-		CloudAccountID uint
-		Total          int
-	}
-	var serverCounts []accountServerCount
-	h.db.Model(&model.Server{}).
-		Select("cloud_account_id, COUNT(*) AS total").
-		Where("cloud_account_id IS NOT NULL").Group("cloud_account_id").Scan(&serverCounts)
-	countByAccount := make(map[uint]int, len(serverCounts))
-	for _, item := range serverCounts {
-		countByAccount[item.CloudAccountID] = item.Total
-	}
-	for index := range accounts {
-		if total, ok := countByAccount[accounts[index].ID]; ok {
-			accounts[index].ServerCount = total
-		}
-	}
 
 	c.JSON(http.StatusOK, model.Response{
 		Code:    200,