ci: TRACES_DB_PATH and RESULTS_PATH defined as relative paths

ci: TRACES_DB_PATH and RESULTS_PATH defined as relative paths

RESULTS_PATH and RESULTS_PATH, as variables in the module context, are
resolved one single time, only during the first module loading. If the
the Python code in execution changes the current dir at some point,
those paths are not going to be updated anymore keeping the paths
wrongly pointing to the old working dir.

This change modify the definition of those variables to use simply
relative paths.

Signed-off-by: Pablo Saavedra <psaavedra@igalia.com>
Reviewed-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>
Reviewed-by: Andres Gomez <agomez@igalia.com>
Reviewed-by: Rohan Garg <rohan.garg@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4916>