Disable gdefault in vim

Since this option is deprecated because it may break stuff in plugins
that do not expect this option to be set.
Also inccommand still highlights globally as soon as the flag is added.

.config/vim/vimrc

@@ -50,10 +50,6 @@ set spell spelllang=en_us
 if (has('nvim'))
 	set inccommand=nosplit
 endif
-" By default substitute with g flag (useful for inccommand and since I never
-" substitute without the g flag.
-" Specify g again to toggle it back
-set gdefault
 
 " Aesthetics ###################################################################
 " Use 24-bit (true-color) mode