Resolver - Fix bottom spacing issue with edge-to-edge

When the button bar renders multiple times, as is the case when using
the back button from Settings, the bottom padding keeps getting
increased to make the list creep upwards. Set the padding to a fixed
number rather than keep adding to it.

Bug: 132114008
Test: Manual
Change-Id: Iab07fdbf7eb3373f354bb3825a3bd18df141f608