more dynamic definition of ‘built-in’ templates

### The required feature described as a wish

As a User/Admin/Operator I would like to install up to date builtin templates for new installations.

As a possible solutions it could not install any default or have it overwritten by a parameter or setting on installation or zone creation.

該 issue 沒有指出檔案、測試或進入點。首先釐清在安裝和建立區域期間應如何選取或覆寫內建模板，然後找出相關的 CloudStack 工作流程。完成的標準是：新的安裝可以使用最新的模板，且選定的預設或覆寫行為已被記錄並經過測試。

由索引模型根據 Issue 內容生成。