Use new libquotient functionality to encrypt direct chats by default

Needs https://github.com/quotient-im/libQuotient/pull/730

src/neochatconnection.cpp

@@ -346,9 +346,6 @@ void NeoChatConnection::openOrCreateDirectChat(User *user)
         }
     }
     requestDirectChat(user->id());
-    connectSingleShot(this, &Connection::directChatAvailable, this, [=](auto room) {
-        room->activateEncryption();
-    });
 }
 
 qsizetype NeoChatConnection::directChatNotifications() const