Update CTS ConnectivityManager tests to work with L release.

Removed most of getNetworkPreference() and setNetworkPreference() tests as
these functions are now fully deprecated and do nothing.  Just test that
they are still callable.
Adjust startUsingNetworkFeature() and stopUsingNetworkFeature() failure
codes to match new behavior.
Tested on devices with Wifi and Cellular radios, and Wifi-only.

bug:17417896
bug:17354855
Change-Id: Iea8b25e399f4e5b6ec3d2101ebf520f89697c4da