Settings dialog: remove the code that was updating the account icon

I just wanted to fix the warning:
 QObject::connect: No such slot OCC::SettingsDialog::slotUpdateAccountIcon(QIcon) in settingsdialog.cpp:108

It turns out we don't need anymore the signal or any of the code that
was updating the account icon in the settings dialog since it we now have a fixed icon
Connection Validator:  Fix connection warning

The timeout signal does not exist.
Timeout is handled as a normal network arror.