Consider using password form element in plugin configuration form

Thanks @dieterholvoet,
I realize now that there might be an issue also with this part as it shows the user/pass in clear (placeholder) when we use config override:

if ($value !== $original) {
  $form[$child]['#placeholder'] = $value;
  $form[$child]['#disabled'] = TRUE;
  $form[$child]['#description'] = $this->t('This config cannot be changed because it is overridden.');
}

It has a certain downside: I will have to enter the password every time I want to change the settings
Maybe we can add a checkbox, similar too
https://git.drupalcode.org/project/symfony_mailer_lite/-/blame/1.0.x/src...

Yeah, you're right. Let's just not do this then. Don't you agree it's a bit unnecessary to try and hide the password on a non-public, admin settings form?