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

从 server/src/main/java/com/cloud/api/query/QueryManagerImpl.java 中的 searchForTemplatesInternal 开始，然后跟踪 listIsos 和 listTemplates 工作流及其直接的 DAO 操作。当工作流完成模块化、服务层职责得到改进、添加日志记录，并且单元测试覆盖变更后的行为时，重构即完成。

由索引模型根据 Issue 内容生成。