Remove dead hidden ConnectivityManager and NetworkInfo APIs.

- There are no callers of
  NetworkInfo.setIsConnectedToProvisioningNetwork(), so remove all the
  code that deals with mIsConnectedToProvisioningNetwork being true,
  including the two ConnectiviyManager APIs.
- There are no callers of
  ConnectivityManager.getMobileRedirectedProvisioningUrl(), so remove
  the code that reads this URL.
- There are no callers of
  ConnectivityManager.captivePortalCheckCompleted(), so remove this
  API which is currently a no-op.

Change-Id: Ifa44c7553c7c45ebe261a2a124d9bf8d6f96c690