[PLT-6496] Remove System Console and config settings for image height and width (#6688)

* remove System Console and config settings for image height and width

* add constants and update config.json

* updated as per review

webapp/components/admin_console/admin_sidebar.jsx

@@ -529,6 +529,7 @@ export default class AdminSidebar extends React.Component {
                                 }
                             >
                                 <AdminSidebarSection
+                                    key='storage'
                                     name='storage'
                                     title={
                                         <FormattedMessage
@@ -537,15 +538,6 @@ export default class AdminSidebar extends React.Component {
                                         />
                                     }
                                 />
-                                <AdminSidebarSection
-                                    name='images'
-                                    title={
-                                        <FormattedMessage
-                                            id='admin.sidebar.images'
-                                            defaultMessage='Images'
-                                        />
-                                    }
-                                />
                             </AdminSidebarSection>
                             <AdminSidebarSection
                                 name='customization'