[WifiSetup] Update connection state for auto-finish

In Wi-Fi setup, when the connection state changed, query
ConnectivityManager for the latest Wi-Fi connection state instead of
relying the NetworkInfo attached in the intent, because the first
network info upon changing AP still shows the network as connected.

Bug: 17511772
Change-Id: I9c7765086dc8fbc5e1c2a37124ca89db3eab04a3