[PLT-7219] Fix username as default for Teammate Name Display setting (#7023)

* fix username as default for Teammate Name Display setting

* update localizeMessage at UsersAndTeamsSettings

webapp/components/admin_console/users_and_teams_settings.jsx

@@ -193,9 +193,9 @@ export default class UsersAndTeamsSettings extends AdminSettings {
                 <DropdownSetting
                     id='teammateNameDisplay'
                     values={[
-                        {value: Constants.TEAMMATE_NAME_DISPLAY.SHOW_USERNAME, text: Utils.localizeMessage('admin.team.showUsername', 'Show username')},
+                        {value: Constants.TEAMMATE_NAME_DISPLAY.SHOW_USERNAME, text: Utils.localizeMessage('admin.team.showUsername', 'Show username (default)')},
                         {value: Constants.TEAMMATE_NAME_DISPLAY.SHOW_NICKNAME_FULLNAME, text: Utils.localizeMessage('admin.team.showNickname', 'Show nickname if one exists, otherwise show first and last name')},
-                        {value: Constants.TEAMMATE_NAME_DISPLAY.SHOW_FULLNAME, text: Utils.localizeMessage('admin.team.showFullname', 'Show first and last name (default)')}
+                        {value: Constants.TEAMMATE_NAME_DISPLAY.SHOW_FULLNAME, text: Utils.localizeMessage('admin.team.showFullname', 'Show first and last name')}
                     ]}
                     label={
                         <FormattedMessage