Remove shell transition animations when showDesktopApps is called

This is used when tapping on desktop in recents.
The current shell transitions do not look good in this case. We likely
need some new animation that works well here.
Setting the transition type to NONE right now which looks better than
with the TO_FRONT animation.

Bug: 267364407
Test: atest DesktopModeControllerTest DesktopTasksControllerTest
Change-Id: Ie945b19a7bca931169403e9642b5cbf2df5bda22