Remove hidden API usage of isNetworkSupported

isNetworkSupported(TYPE_MOBILE) is equivalent to
TelephonyManager.isDataCapable, as the former is set based on the
latter.

Bug: 182859030
Test: atest CarrierConfigManagerTest
Change-Id: Iaf5e8c193ff7e20475e2a25c89a58a6cbaff538d
diff --git a/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java b/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java
index 97c8a51..f9175be 100644
--- a/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java
+++ b/tests/tests/telephony/current/src/android/telephony/cts/CarrierConfigManagerTest.java
@@ -43,7 +43,6 @@
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.PackageManager;
-import android.net.ConnectivityManager;
 import android.os.Looper;
 import android.os.PersistableBundle;
 import android.platform.test.annotations.SecurityTest;
@@ -107,9 +106,7 @@
      * the device supports cellular data.
      */
     private boolean hasTelephony() {
-        ConnectivityManager mgr =
-                (ConnectivityManager) getContext().getSystemService(Context.CONNECTIVITY_SERVICE);
-        return mgr.isNetworkSupported(ConnectivityManager.TYPE_MOBILE);
+        return mTelephonyManager.isDataCapable();
     }
 
     private boolean isSimCardPresent() {