[FIX] Allow mangohud to find its config file again

[Etaash-mathamsetty]

Basically title, without this patch it wasn't finding the config file because we were setting XDG_CONFIG_HOME to something different thanks to another PR.

Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[flavioislima]

LGTM

[flavioislima]

@Etaash-mathamsetty we can merge this after fixing the conflicts