ci/traces: Always generate the junit XML.

While it's not the primary interface to interpreting trace job failures,
it was set in all the traces jobs it looks like and it's low cost anyway.

Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14604>

.gitlab-ci.yml

@@ -1289,7 +1289,6 @@ debian-mingw32-x86_64:
   variables:
     CI_JOB_JWT_FILE: /minio_jwt  # JWT file on piglit jobs should be available on / partition
     PIGLIT_REPLAY_EXTRA_ARGS:  --keep-image --db-path ${CI_PROJECT_DIR}/replayer-db/ --minio_host=minio-packet.freedesktop.org --minio_bucket=mesa-tracie-public --role-session-name=${CI_PROJECT_PATH}:${CI_JOB_ID} --jwt-file=${CI_JOB_JWT_FILE}
-    PIGLIT_JUNIT_RESULTS: 1
     CI_JOB_JWT_FILE: /minio_jwt  # JWT file on piglit jobs should be available on / partition
   script:
     - install/piglit/piglit-traces.sh