Use default network template in billing cycle settings.

- if the network template is not set in the bundle arguments, use the
default network template for getting the billing data.
- change to use ConnectivityManager.from(context) in DataUsageUtils to
be consistent with the usage in other methods.

Change-Id: I25eb27f8f26d9ecafc66aa2c69806e94c6b63499
Fixes: 117452991
Test: make RunSettingsRoboTests

tests/robotests/src/com/android/settings/datausage/DataUsageSummaryPreferenceControllerTest.java

@@ -121,7 +121,7 @@ public class DataUsageSummaryPreferenceControllerTest {
 
         mActivity = spy(Robolectric.buildActivity(FragmentActivity.class).get());
         when(mActivity.getSystemService(TelephonyManager.class)).thenReturn(mTelephonyManager);
-        when(mActivity.getSystemService(ConnectivityManager.class))
+        when(mActivity.getSystemService(Context.CONNECTIVITY_SERVICE))
                 .thenReturn(mConnectivityManager);
         when(mTelephonyManager.getSimState()).thenReturn(TelephonyManager.SIM_STATE_READY);
         when(mConnectivityManager.isNetworkSupported(TYPE_WIFI)).thenReturn(false);