test_const_string: add expected result for untouched value
test_const_string: add expected result for untouched value

Based on PR #7057 feedback

Co-authored-by: stuartarchibald <bea6903cc29f240e46cd18ca8cb3cffc8245594f@users.noreply.github.com>
seibert/numba,IntelLabs/numba,seibert/numba,numba/numba,seibert/numba,cpcloud/numba,cpcloud/numba,cpcloud/numba,IntelLabs/numba,IntelLabs/numba,seibert/numba,cpcloud/numba,numba/numba,IntelLabs/numba,numba/numba,numba/numba,seibert/numba,cpcloud/numba,IntelLabs/numba,numba/numba