Fix test for echoing messages

The previous linter rule about stray echo lines has been restored, and
now all problems for custom linting rules can be ignored by adding a
comment above problem lines.

autoload/ale/toggle.vim

@@ -64,7 +64,8 @@ function! ale#toggle#ToggleBuffer(buffer) abort
     " Disabling ALE globally removes autocmd events, so we cannot enable
     " linting locally when linting is disabled globally
     if l:enabled && !g:ale_enabled
-        execute 'echom ''ALE cannot be enabled locally when disabled globally'''
+        " no-custom-checks
+        echom 'ALE cannot be enabled locally when disabled globally'
 
         return
     endif