[Windows] Split Tunneling: uploading relatively big site list causes memory leak

[Rebel028]

Describe the bug
Uploading relatively big site list causes memory leak. After restarting the app it's impossible to reset the list because it requires to load the whole list into the UI (that causes memory leak again). Mentioned in #1135 but was not solved

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Settings'->'Connection'->'Site-based split tunneling'
2. Click on three dots then 'import'
3. Choose file for import: amnezia_sites.json (this file is very big but you can reproduce in with file from Client hangs and crashes on boot when there are too many sites in the Split tunneling site list #1135)
4. Application starts consuming RAM like crazy

Expected behavior
List is loaded successfully and app is usable

Log files
Logs are enabled in settings, but no logs are written

Desktop (please complete the following information):

• OS: Windows 11
• Version 4.8.1.9

Additional context

Related issues:

• Client hangs and crashes on boot when there are too many sites in the Split tunneling site list #1135
• [UI] Implement pagination of the list of domains and IP addresses, as well as the list of applications. Alternative: uploading the following 10 domains (applications) when scrolling, if necessary. #1161
• Split tunneling import crashes the app (Windows client) v #1139
• Split tunneling freezes crashes MacOS client #975

It probably has something to do with client/ui/controllers/sitesController.cpp and I would gladly fixed it myself if I'd ever worked with Qt and C++