Use different intensity values for light and dark Breeze themes
Currently, a positive brightness value is set in the Breeze theme regardless of the colorscheme. Instead, let's use the colorscheme-dependent fallback and update its values to be closer to the ones used in Breeze.
BUG: 455173 CCBUG: 480548 FIXED-IN: 6.0
(cherry picked from commit 0e53a6db)