Don't send groups in contact sync message

js/models/messages.js

@@ -2008,7 +2008,7 @@
             }
           });
         } else if (newGroup) {
-          // We have an unknown group, we should request info
+          // We have an unknown group, we should request info from the sender
           textsecure.messaging.requestGroupInfo(conversationId, [
             primarySource,
           ]);

libloki/api.js

@@ -109,8 +109,9 @@
   }
   async function createContactSyncProtoMessage(conversations) {
     // Extract required contacts information out of conversations
+    const sessionContacts = conversations.filter(c => c.isPrivate());
     const rawContacts = await Promise.all(
-      conversations.map(async conversation => {
+      sessionContacts.map(async conversation => {
         const profile = conversation.getLokiProfile();
         const number = conversation.getNumber();
         const name = profile