fix(calendar(js)): avoid call to /members when expansion is disabled

Expose SOGoLDAPGroupExpansionEnabled in /jsonDefaults to avoid a call to
/members when the parameter is disabled.

UI/WebServerResources/js/Scheduler/Attendees.service.js

@@ -182,7 +182,7 @@
         if (!_.find(this.attendees, function(o) {
           return o.email == attendee.email;
         })) {
-          if (card.$isList()) {
+          if (card.$isList() && Attendees.$Preferences.defaults.SOGoLDAPGroupExpansionEnabled) {
             // LDAP list -- preload members
             card.$members().then(function(members) {
               attendee.members = members;