Update UNIT_TEST_RESULTS="./unit_test_results.txt" to use an absolute path

[theqin0]

In multiple run_repo_invariants scripts, we use this file path to store test output

UNIT_TEST_RESULTS="./unit_test_results.txt"

People usually cd codebase and then write to UNIT_TEST_RESULTS, which writes to /codebase (not desirable). To make matters worse, this doesn't get cleaned up