Update the flyout width to be smaller on large screens

On phone we use 60% of the screen which is huge on
tablet. This change uses 30% of the screen for the
flyout on large screens & enforces a minimum for
that value.

Test: manual - get a long message in a bubble on a
               tablet, it should have similar width
               as it does on phone.
Bug: 186776550
Change-Id: I500c566edd9941dc2bd149692eaf95c6e6f4aa61