@complete annotation in commands references class that doesn't exist

[joachim-n]

Several @complete annotations reference the class Drush\Commands\CompletionCommands, which AFAICT doesn't exist. Eg:

     * @complete \Drush\Commands\CompletionCommands::completeModules

[weitzman]

Yes, these complete annotations and methods should be removed for now.

[greg-1-anderson]

Once we are using the Symfony dispatcher, we can autocomplete with https://github.com/bamarni/symfony-console-autocomplete