[GridDelegate] Remove lightening overlay on hover
This overlay causes the colors of the hovered item to be distorted, which may be a problem when the content's color matters--for example when selecting a new color scheme!
There is an outline effect on hover that differs from the selection effect, so that should be enough to denote that an item is hovered.
Also the lightening effect is is currently hardcoded to not exist on mobile, so let's just remove it on the desktop view to be consistent.
BUG: 438462 FIXED-IN: 5.84
cc @teams/vdg @mart
IIRC this was originally done to make grid items more closely resemble hovered files in Dolphin's grid view, but this is incorrect because the UX is different, so it should not be trying to visually mimic something it's not.
Edited by Nate Graham