ci/piglit: fix parallel piglit results

ci/piglit: fix parallel piglit results

Commit bcea453d4a6 removed the summary from the expected piglit
results, but handling of results when using parallel jobs was also doing
the same, which ends up on removing too many lines from results.

Fixes: bcea453d4a6 ("ci/piglit: Stop including the test counts at the
end of expectations.")

Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9286>