disco: Don't query for #items on conference components.

We don't need them at that time and we'll query when a chat room gets opened.

src/converse-disco.js

@@ -80,8 +80,8 @@
                 },
 
                 queryForItems () {
-                    if (_.isEmpty(this.identities.where({'category': 'server'})) &&
-                        _.isEmpty(this.identities.where({'category': 'conference'}))) {
+
+                    if (_.isEmpty(this.identities.where({'category': 'server'}))) {
                         // Don't fetch features and items if this is not a
                         // server or a conference component.
                         return;