Remove special support for D8 in 911-get-stack-trace

This test produced slightly different output when run using D8 compared
with DX. As D8 is the default and DX is no longer used this removes the
special support for D8 and updates the expected output to match.

Test: art/test/testrunner/testrunner.py
Change-Id: Icd1f4e547c13bf6641202ac086d567895e1b83a4
3 files changed