Use active instead of available subscriptions in 2 places

In a couple of places we were showing DSDS UI using the list of
*available* subscriptions instead of the list of *active* ones. This
difference is relevant for instance if you have multiple eSIM profiles -
in typical hardware only one of those can be active at one time. This CL
fixes that problem in two places:

1) The header at the top of the Network & internet page

2) The ListPreference's on the mobile network detail page for selecting
   the default subscription for Calls / SMS.

Fixes: 129673046
Test: make RunSettingsRoboTests
Change-Id: I891c856bdd4516286fcee1067684d9161ceaca80

src/com/android/settings/network/SubscriptionsPreferenceController.java

@@ -129,7 +129,7 @@ public class SubscriptionsPreferenceController extends AbstractPreferenceControl
         mSubscriptionPreferences = new ArrayMap<>();
 
         int order = mStartOrder;
-        for (SubscriptionInfo info : SubscriptionUtil.getAvailableSubscriptions(mManager)) {
+        for (SubscriptionInfo info : SubscriptionUtil.getActiveSubscriptions(mManager)) {
             final int subId = info.getSubscriptionId();
             Preference pref = existingPrefs.remove(subId);
             if (pref == null) {
@@ -216,7 +216,7 @@ public class SubscriptionsPreferenceController extends AbstractPreferenceControl
         if (mSubscriptionsListener.isAirplaneModeOn()) {
             return false;
         }
-        return SubscriptionUtil.getAvailableSubscriptions(mManager).size() >= 2;
+        return SubscriptionUtil.getActiveSubscriptions(mManager).size() >= 2;
     }
 
     @Override