Fix notices on Task.tpl (grumpy mode)

Fix notices on Task.tpl (grumpy mode)

The addition of group.id to this id dates back to
https://github.com/civicrm/civicrm-core/pull/3191

- a huge PR which attempted to block collisions on the data table id per
https://issues.civicrm.org/jira/browse/CRM-14636

However, I could find no evidence that 'group' would ever be assigned here
and as a rather large PR I suspect there was a bit of pattern replacement
beyond what was confirmed....

Removing 'group' means the selector becomes 'selectedRecords-' - which is
what it is in practice anyway since group is not assigned. This is possibly
accidentally unique anyway because of the trailing '-'