Tune overview icon size and paddings

- Tune overview icon size and paddings across form factors
- Limit handheld overview to 70% of screen width

Fix: 209981696
Test: manual
Change-Id: I946b9bb2e9eb05cdc1e4497b9b1267a91731a8e1

src/com/android/launcher3/DeviceProfile.java

@@ -1129,7 +1129,7 @@ public class DeviceProfile {
             return  ((taskbarSize - overviewActionsHeight) / 2) + getTaskbarOffsetY();
         }
 
-        return 0;
+        return isTaskbarPresent ? stashedTaskbarSize : mInsets.bottom;
     }
 
     /** Gets the space that the overview actions will take, including bottom margin. */