Get rid of a weird shadow background when rendering smartspace in preview

I think it has something to do ripple background, clipChildren, focusable, clickable, etc. My previous projects ran into related issues before, which is why I tried to set focusable here to false. Let me know if you have a better idea of what exactly is going on

FYI, I also did go back to my previous CL and confirmed that it's necessary.

Fixes: 152278370
Test: Factory reset the phone (with latest build and launcher built from this CL). Make sure no background is shown
Change-Id: I401ffcccd1e07a3c0beb5ed460a707d25bddf41e