Add task-id to animation leash

This was removed by an earlier CL because we thought it
wasn't needed, but since snapshots have moved up one level
(sibling of task), it turns out that this is still needed
so adding it back.

Bug: 151881448
Test: do a transition and see taskid in surface trace
Change-Id: I4b48447f7d235e9828ac886f23a567668f1184cd