Fix check indicator covering update in multiselect.

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationUpdateItem.java

@@ -232,7 +232,7 @@ public final class ConversationUpdateItem extends FrameLayout
 
   @Override
   public @Nullable View getHorizontalTranslationTarget() {
-    return null;
+    return background;
   }
 
   static final class RecipientObserverManager {