Log: fencer: drop useless logs

fenced_handle_manual_confirmation() already logs a notice, so
initiate_remote_stonith_op() doesn't need to log another

Similarly, async_action_complete() already logs a debug when a fence action
completes, and log_async_result() will log another debug with a little more
information, so we don't need a third debug from stonith_action_async_done()

Then, fenced_process_fencing_reply() logged the same information finalize_op()
does right before calling it, so don't do that.

Finally, a debug log that just says "sending args" for a fencing action is
rather useless.