[OpenMP][OMPT] Remove unused var in archer (#201140)
Working on enabling the build of OpenMP and Offload in pre-merge checks
surfaced this unused var and pre-merge checks run with -Werror.
As I did not see where it should be used, remove the variable to address
the warning.
The pre-merge running into the warning as error is
https://github.com/llvm/llvm-project/actions/runs/26826349862/job/79094823845?pr=174955
