PIM-1359 : Clean products datagrid in group edit view

Bug fix: [yes]
Feature addition: [yes]
Backwards compatibility break: [no]
Unit test passes: [yes]
Behat scenarios passes: [yes]
Checkstyle issues: [no]*
Fixes the following jira:
 - PIM-1359
 - PIM-1440
 - PIM-1441