Do test_getStackTraces last for test 129

Doing this check last leaves time for the heap task daemon to call
TaskProcessor::RunAllTasks. This should hopefully fix the flakiness
of test 129 during startup.

Test: test-art-host-run-test

Bug: 34342857
Change-Id: I85f8d78083092df802728c59a4c86f63be8d949a