Committed Changes for DNN-5909 - GetFoldersByPermission Performance Improvement

Changes to the GetFoldersbyPermission procedure to improve performance.  Change was removing "Users" and "UserRoles" from the last query in the procedure.  These tables are un-used, not returned, and not filtering any data.  Removing these reduce the CPU cost greatly.  Full details on DNN JIRA ticket 5909!
We're in the `ELSE` clause of `IF @PortalID IS NULL`, so the check on this line for `F.PortalID IS NULL AND @PortalID IS NULL` should be able to be removed (though it's probably removed by the query optimizer as well)