fix: set `XDG_CURRENT_DESKTOP` env var back to original value before invoking xdg utils (#45310)
* Fix XDG_CURRENT_DESKTOP before invoking XDGUtil
* apply suggestion
* use existing XDG_CURRENT_DESKTOP const
Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Evan Simkowitz <esimkowitz@users.noreply.github.com>