Revert download to .tmp in frontend_management

[huchenlei]

Partially revert #5152

In electron build, the downloaded file ownership can be taken by the electron app, and cause rename to fail.

Device: cuda:0 NVIDIA GeForce RTX 4090 : cudaMallocAsync
[2024-10-25 17:14:15.902] [error] stderr: Using pytorch cross attention
[2024-10-25 17:14:17.258] [error] stderr: Initializing frontend: Comfy-Org/ComfyUI_frontend@latest, requesting version details from GitHub...
[2024-10-25 17:14:17.452] [error] stderr: Downloading frontend(Comfy-Org_ComfyUI_frontend) version(1.3.22) to (D:\electron\assets\ComfyUI\web_custom_versions\Comfy-Org_ComfyUI_frontend\1.3.22.tmp)
[2024-10-25 17:14:18.642] [error] stderr: Failed to initialize frontend: [WinError 3] The system cannot find the path specified: 'D:\\electron\\assets\\ComfyUI\\web_custom_versions\\Comfy-Org_ComfyUI_frontend\\1.3.22'
Falling back to the default frontend.
[2024-10-25 17:14:18.643] [error] stderr: [Prompt Server] web root: D:\electron\assets\ComfyUI\web

Overall we probably don't want to introduce an extra step that can easily fail to prevent something that is more rare to fail.