CI-tron currently requires a number of minutes to also be set, so let's
just pick some huge value that will never actually trigger, leaving the
OVERALL timeout as the only one that applies.
Fixes: ee5a95319d ("broadcom/ci: automatically reboot rpi3 when they fail to find the root device")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38461>