Messaging: Remove VisibleForTesting

Since we removed all tests, no need to keep those flags around either

Change-Id: Icaf71832c459cecbcbddc75f552c60e48ae95189

src/com/android/messaging/datamodel/data/ConversationParticipantsData.java

@@ -24,8 +24,6 @@ import androidx.collection.SimpleArrayMap;
 
 import com.android.messaging.util.Assert;
 
-import com.google.common.annotations.VisibleForTesting;
-
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
@@ -59,11 +57,6 @@ public class ConversationParticipantsData implements Iterable<ParticipantData> {
         }
     }
 
-    @VisibleForTesting
-    ParticipantData getParticipantById(final String participantId) {
-        return mConversationParticipantsMap.get(participantId);
-    }
-
     ArrayList<ParticipantData> getParticipantListExcludingSelf() {
         final ArrayList<ParticipantData> retList =
                 new ArrayList<>(mConversationParticipantsMap.size());