Use IPv4v6 as default protocol when APN setting is not available

Use IPv4v6 for default protocol and IPv4 for default roaming protocol
when APN setting is not available.

Fix: 258636082
Test: atest DataProfileTest
Change-Id: Ic61fa42f99750e6e48ea1cd08f058af3fd67c551

telephony/java/android/telephony/data/DataProfile.java

@@ -147,7 +147,7 @@ public final class DataProfile implements Parcelable {
         if (mApnSetting != null) {
             return mApnSetting.getProtocol();
         }
-        return ApnSetting.PROTOCOL_IP;
+        return ApnSetting.PROTOCOL_IPV4V6;
     }
 
     /**