Restore look of Wi-Fi panel for Setup Wizard

As part of the Wi-Fi refresh, this CL hides the action bar, menu, and
Settings icon in the context of the Setup Wizard. Dead code related
to WifiSettingsForSetupWizardXL has also been removed.

Bug: 5364589
Change-Id: Ib6716500153879b939a18a7007f1f6521b73890b