Refactor `listTemplates` and `listIsos` workflows

The workflows of the `listIsos` and `listTemplates` APIs, particularly the `com.cloud.api.query.QueryManagerImpl#searchForTemplatesInternal` method, could greatly benefit from refactoring.

This method accepts over 20 parameters, spans approximately 200 lines, performs DAO operations directly from the business/service layer, and lacks modularization, logging, and unit tests. These issues make troubleshooting and maintenance challenging.

https://github.com/apache/cloudstack/blob/f52e05863e608f53f9e97e93fe47577b8dfe189b/server/src/main/java/com/cloud/api/query/QueryManagerImpl.java#L4802-L5007

從 server/src/main/java/com/cloud/api/query/QueryManagerImpl.java 中的 searchForTemplatesInternal 開始，接著追蹤 listIsos 和 listTemplates 工作流程及其直接的 DAO 操作。當工作流程完成模組化、服務層職責獲得改善、加入日誌記錄，且單元測試涵蓋變更後的行為時，重構即完成。

由索引模型根據 Issue 內容生成。