Make getWidgetProviderInfoByProviderName return the correct WidgetItem

for Pixel own widgets.

The pixel own widgets can have categories and getWidgetProviderInfoByProviderName
might not find the right widget if the widget has a category.

Flag: NA
Test: Manaul testing =(
Test: Make sure the placement in the widget picker is correct.
Test: All widgets in widget_section.xml with alsoKeepInApp set to false will previously dissapear on the preview.
Fix: 331628371
Change-Id: I1e4c8ae3dd21f8aef3e4aac99ce6ce6701e94760