SSH: Use Qt5-style connects

The heavy lifting was done by clazy.

Change-Id: I04261849c92c54990f9f142fe541d984c5fb21d3
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>

src/libs/ssh/sshconnectionmanager.cpp

@@ -194,7 +194,6 @@ private:
         connection->moveToThread(qobject_cast<QThread *>(threadObj));
     }
 
-private slots:
     void cleanup()
     {
         QMutexLocker locker(&m_listMutex);