Prevent passing in GroupedTaskView when not animating split launch

* With ag/23320818 we started always passing in GroupedTaskView,
which gets used downstream to mean that we are launching an app
from tapping on it in overview
* This caused a bug in the case where we quickswitched to the last
task. Now we pass in null for GroupedTaskView like before

Test: Prior bug (b/274540670) doesn't occur, nor do repro steps
for this one
Fixes: 289163668
Flag: None

Change-Id: I82dd8f26bfc286fefc0995822786cf3980da41d0