Fix OutlineCloseButton default for close tab buttons
Under Window Decorations, the option "Draw a circle around close button" is unchecked by default. This normally applies to both window and tab close buttons, but tab buttons permanently had the circle visible because this boolean was incorrect.
This made it impossible for the user to disable this style via GUI. OutlineCloseButton=false had to be explicitly added to ~/.config/breezerc.
Fixes a regression that started in the 5.23 cycle.
BUG 448122