Sometimes not all of the jobs execute. For instance, Windows build jobs
will not trigger on AMD-only MRs. Use the 'optional' keyword to ignore
jobs which don't exist in our pipeline.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Fixes: 310e3bb026 ("ci: do not start build-only jobs until the critical build-for-tests jobs are done")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30926>