Removes the background color logic that was incorrectly added to
PageLayoutGridLayout in PR #16870. Grid layouts are only used for
dashboards where widgets have their own background colors set in
WidgetCard.tsx, so the container background was causing visual
mismatches in padding/gap areas. The background logic remains correctly
applied in PageLayoutVerticalListViewer and PageLayoutVerticalListEditor
where widgets need to inherit the container background.
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Co-authored-by: Devessier <baptiste@devessier.fr>
Abdullah.
32efaee1bf