fix: hardcoded paths in p4 L1 fwd test

src/tests/p4-fwd-l1/mininet/2switch1path.py

src/tests/p4-fwd-l1/mininet/4switch2path.py

src/tests/p4-fwd-l1/mininet/6switch2path.py

src/tests/p4-fwd-l1/mininet/8switch3path.py

src/tests/p4-fwd-l1/run_test_01_bootstrap.sh

src/tests/p4-fwd-l1/run_test_02_create_service.sh

src/tests/p4-fwd-l1/run_test_03_delete_service.sh

src/tests/p4-fwd-l1/run_test_04_cleanup.sh

src/tests/p4-fwd-l1/setup.sh

src/tests/p4-fwd-l1/tests/Objects.py