Remove createWindowContext in Launcher preview renderer

The line causes an error in Window Manager. When removed, it doesn't
seem to have an effect for the Wallpaper Picker use case. The preview
render still shows correctly after config changes including rotation
and dark/light theme because the picker restarts and re-requests a
preview.

Flag: NA
Bug: 328089367
Test: manually tested with config changes and different lifecycle cases
Test: manually tested with multi crop flag on and off
Change-Id: Id1bd30c7ab4c50d29622b647bd368aafbd5c043f