Since $RESULTS_DIR is now centrally defined in setup-test-env.sh it's no
longer necessary to manually add a hard-coded results directory for the
b2b-test job results.
This keeps the results directory consistent between b2c-test jobs and lava.
Fixes: 9b6d14aed1 ("ci: Always create results dir from init")
(cherry picked from commit 276447ef81)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32119>