Stop expecting WifiConfig extra from CONFIGURED_NETWORKS_CHANGED_ACTION broadcast

WifiConfig is no longer sent in this broadcast
due to privacy concerns, so stop reading this
extra. Instead, query WifiManager to find the
matching WifiConfiguration to update.

Bug: 158874479
Test: make RunSettingsRoboTests -j40 ROBOTEST_FILTER="com.android.settings.wifi.details.WifiDetailPreferenceControllerTest"
Change-Id: Ie52339220acbbe111a6aa5f785fbfa409c405b5b