Remove log handler configuration from Worker.work method

Log handlers do not need to be installed by the `work` method. The two entry points for starting a worker are:
- The built-in rq worker. It calls `setup_loghandlers` already.
- Custom worker. Applications that call `work()` are probably doing it so they can do configuration before starting the worker. This would normally include configuring logging.

In the case where an application has created its own worker and not configured logging, then the default root log handler is used. If they are not happy with that, then `setup_loghandlers` can always be called anyway.