restore require once command for non app files

core/ajax/appconfig.php

core/ajax/grouplist.php

core/ajax/translations.php

core/ajax/userlist.php

core/ajax/validateuser.php

core/ajax/vcategories/add.php

core/ajax/vcategories/delete.php

core/ajax/vcategories/edit.php

core/lostpassword/index.php

core/lostpassword/resetpassword.php

ocs/providers.php

ocs/v1.php

search/ajax/search.php

search/index.php

settings/admin.php

settings/ajax/changepassword.php

settings/ajax/creategroup.php

settings/ajax/createuser.php

settings/ajax/disableapp.php

settings/ajax/enableapp.php