Dropbox > Group/Section filter visibility is hard-coded to true; should be based on permissions

SAK-14625 introduced a drop down control to filter the list on groups or sections. The boolean value that determines if this control is rendered was hard-coded to true. The correct approach is to conditionally render this control based on if the user has one of two permissions (dropbox.maintain or dropbox.maintain.own.groups). If the user doesn't have either of these permissions, it's not appropriate to display the drop down filter.