use proper tag / after tags for automatic grouping / ungrouping

This fixes random failures of test_automatically_setting_grouping_reference_same_group and test_automatically_unsetting_grouping_reference_when_cancelling

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@30886 20353a03-c40f-0410-a6d1-a30d3c3de9de