ART-tests: Remove DX-dependency from 618-checker-induction.

In some test cases D8 generates PHI nodes in different order than DX. This
CL updates the numbering of PHI nodes in the CHECK conditions in those
cases and enables D8.

Test: art/test.py -r -b --host -t 618-checker-induction
      Tested locally with --target/--gcstress.
Bug: 65168732

Change-Id: Ibef8ae37a7924aa12ac496ab5db5d8088e94617a