[vim] remove unnecessary config for deleted rainbow plugin
change
commit 23ccb52117c8edffc8529e1a539c2360eee9375d
author Alpha Chen <alpha.chen@gmail.com>
date
parent 44990aae 
diff --git a/.vimrc b/.vimrc
index 9bb1b28b..995c92bb 100644
--- a/.vimrc
+++ b/.vimrc
@@ -204,9 +204,6 @@ if executable('fzf')
   nmap <Leader>t :Tags<CR>
 endif
 
-" rainbow
-let g:rainbow_active = 0
-
 " gundo
 nnoremap <leader>u :GundoToggle<CR>