Remove code that assumes single GroupedTaskView

* Old code assumes there will only be a single
GroupedTaskView, removing those code paths helps
consolidate single and grouped task code flows
* Correctly check when we need to add a stub
taskView for GroupedTaskViews by checking each
individual taskId

Test: Swiping with multiple split pairs doesn't
cause a cycle
Fixes: 213355942

Change-Id: Ibb98ae0dfcd4f52b762685aec9d2ee6445b9ef54