Change SubMgrTest to use public methods instead of hidden ones

The getActiveSubscriptionIdList is hidden so it cannot be used in cts
tests. Alternatively, getActiveSubscriptionInfoList is public and can be
accessed via CTS test. Change the testSetpreferredDataSubscriptionId()
test to use the public one.

Bug: 136733847
Test: CTS
Change-Id: I09950212f9f551dfb52dc55de9094ec57ad860e9
(cherry picked from commit ac15baaaebc9d1e0e7b06d63b06bc21ef727edb5)
diff --git a/tests/tests/telephony/current/src/android/telephony/cts/SubscriptionManagerTest.java b/tests/tests/telephony/current/src/android/telephony/cts/SubscriptionManagerTest.java
index 0832528..6803431 100644
--- a/tests/tests/telephony/current/src/android/telephony/cts/SubscriptionManagerTest.java
+++ b/tests/tests/telephony/current/src/android/telephony/cts/SubscriptionManagerTest.java
@@ -43,6 +43,8 @@
 import android.telephony.SubscriptionPlan;
 import android.telephony.TelephonyManager;
 
+import androidx.test.InstrumentationRegistry;
+
 import com.android.compatibility.common.util.ShellIdentityUtils;
 import com.android.compatibility.common.util.SystemUtil;
 import com.android.internal.util.ArrayUtils;
@@ -66,8 +68,6 @@
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
-import androidx.test.InstrumentationRegistry;
-
 public class SubscriptionManagerTest {
     private SubscriptionManager mSm;
 
@@ -550,10 +550,11 @@
             }
         };
 
-        int [] subList = mSm.getActiveSubscriptionIdList();
+        List<SubscriptionInfo> subscriptionInfos = mSm.getActiveSubscriptionInfoList();
         boolean changes = false;
 
-        for (int subId : subList) {
+        for (SubscriptionInfo subInfo : subscriptionInfos) {
+            int subId = subInfo.getSubscriptionId();
             if (subId != preferredSubId) {
                 int newPreferredSubId = subId;
                 // Change to a new value.