[Wi-Fi] Remove the files which use SettingsLib Wi-Fi objects

This change removes

WifiDetailPreferenceController
WifiPrivacyPreferenceController

Bug: 152571756
Test: make RunSettingsRoboTests ROBOTEST_FILTER=WifiConfigControllerTest
      Manualy add a Wi-Fi network of randomized MAC and a Wi-Fi network of device MAC
      in SetupWizard, then observe the MAC value in Settings Wi-Fi detail.
Change-Id: I82ef4e1d2c386d8bd751df8ff18c18163a0e9a6a