Clear padding and background after create view from context.

When create view with Context, there will also load some view
attributes from the Context and pre-set to the View object, to ensure
the splash screen view not affected by those attributes, clear padding
and background after create those view objects.

Bug: 191339594
Test: manual launch several apps from Launcher/Notification.
Tets: atest SplashscreenTests
Change-Id: I05be9c296a04cd49a0896ad8aef57643720d60ce