lookandfeelmanager: Write colors before color scheme

While we indeed write both with KConfig::Notify flag interested
processes might only listen to the scheme change instead of
every color scheme group. When they react to the scheme change
the colors have not yet changed.
The colors kcm also does it in this order.
BUG:421745
FIXED-IN:5.24.7


(cherry picked from commit 9a77503f)