vim: Drop textwidth autocmd for native way

Instead of needing a manual autocmd that triggers on textwidth changes,
colorcolumn supports offsets to textwidth natively.

.config/vim/vimrc.d/30-settings.vim

@@ -42,9 +42,9 @@ else
 	nmap cW dWi
 endif
 " Highlight current line
-" set cursorline
-" Show ruler at &textwidth columns
-let &colorcolumn=&textwidth
+"set cursorline
+" Show ruler at column behind &textwidth
+set colorcolumn=+1
 " Show menu for possible matches when using command-line completing.
 if (has('wildmenu'))
 	set wildmenu

.config/vim/vimrc.d/80-autocommands.vim

@@ -57,9 +57,6 @@ endif
 " Custom bindings when debugging
 autocmd SourcePost termdebug.vim tnoremap <Esc> <C-\><C-n>
 
-" Adjust the colorcolumn together with &textwidth
-autocmd OptionSet textwidth exec 'set cc-=' . v:option_old . ' | set cc+=' . &tw
-"
 " Highlight word under cursor
 augroup highlight_current_word
 	au!