[Media Recs] Some updates to smartspace recommendations layout:

 - Only show 3 albums instead of 6
 - Remove padding from app icon
 - Update various sizes

This updates both the expanded and collapsed layouts.

Bug: 223603970
Test: manual (see bug comment for screenshot)
Test: atest SystemUITests
Change-Id: I5c22b38b6195658ae47c1a48289bac71d0f92567