Disabled task snapshot for IoT devices

Disable this function for IoT devices, since many of them
don't have the display and are running low on RAM.
Also, some IoT devices crash when taking snapshot.

Bug: 62182164
Test: System service does not crash when user app dies on IoT device
Change-Id: I4e1e8ef27e4e7e3525f0051349dc8bacd6436ba1