fix: fix use-after-free bug in config reparse

Fixed a use-after-free bug where the file pointer was being deleted
before being reassigned, which could lead to dangling pointer issues.
Replaced manual deletion with std::unique_ptr to ensure proper ownership
transfer and automatic cleanup.

Influence:
1. Test config file reloading functionality
2. Verify no crashes occur during config refresh operations
3. Test multiple consecutive config reparse operations
4. Verify memory management is handled correctly

fix: 修复配置重新解析中的释放后使用错误

修复了一个释放后使用的错误，其中文件指针在重新分配之前被删除，可能导致悬
空指针问题。使用 std::unique_ptr 替换手动删除操作，确保正确的所有权转移
和自动清理。

Influence:
1. 测试配置文件重新加载功能
2. 验证配置刷新操作期间不会发生崩溃
3. 测试多次连续的配置重新解析操作
4. 验证内存管理是否正确处理

Author: 18202781743

dconfig-center/dde-dconfig-daemon/dconfigresource.cpp

@@ -161,8 +161,7 @@ bool DSGConfigResource::reparse(const QString &appid)
     }
 
     // config refresh.
-    delete file;
-    file = nullptr;
+    std::unique_ptr<DConfigFile> oldConfig(file);
     m_files[resouceKey] = config.release();
 
     // emit valuechanged.