Fix Select2 Suggestion widget in layout demo

Select2 suggestions widget in layout demo are broken. This is because there is no long running conversation but for the nuxeo-select2.js code currentConversationId != null means there is a a long running conversation.

In the generated html page, we have var currentConversationId = '1898';

Therefore it tries to restore Seam Conversation context and ... it crashes. When the currentConversationId starts with 0NXMAIN, this means there is a long running conversation? And when it does not, this is a temporary one?