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

src/com/android/settings/datausage/DataUsageUtils.java

@@ -172,8 +172,7 @@ public final class DataUsageUtils {
             return SystemProperties.get(TEST_RADIOS_PROP).contains("wifi");
         }
 
-        ConnectivityManager connectivityManager =
-                context.getSystemService(ConnectivityManager.class);
+        final ConnectivityManager connectivityManager = ConnectivityManager.from(context);
         return connectivityManager != null && connectivityManager.isNetworkSupported(TYPE_WIFI);
     }