Remove .ss-tabset class from CMSMain forms, confuses tab state setting.
Remove .ss-tabset class from CMSMain forms, confuses tab state setting.

It is already applied to the parent template container,
which means that tab state finds two nested sets,
setting the wrong id (#Root instead of #pages-controller-cms-content

jonom/silverstripe-cms,silverstripe-labs/silverstripe-reports,silverstripe/silverstripe-siteconfig,dhensby/silverstripe-cms,silverstripe-labs/silverstripe-reports,silverstripe/silverstripe-cms,jonom/silverstripe-cms,dhensby/silverstripe-reports,helpfulrobot/i-lateral-silverstripe-siteconfig,dhensby/silverstripe-reports,silverstripe/silverstripe-cms,dhensby/silverstripe-cms,dhensby/silverstripe-cms