WIXUI toolkit based setups fails to detect the installation dir as writable

ReactOS Version 0.4.15-amd64-dev
Build 20240410-0.4.15-7878-gd05dcf6.MSVC_19.2428314.0

Steps to reproduce:

• Download a WIXUI toolkit based software (like SuperTux x64 from RAPPS)
• Starts the installation and choose a directory on a fixed disk
• Installation complains about to choose a valid disk

The custom action's WixUIValidatePath fails to check admin rights.
It can however be skipped by passing the WIXUI_DONTVALIDATEPATH parameter like:

msiexec /i Supertux.msi WIXUI_DONTVALIDATEPATH="1"