ci/bare-metal: Retry booting chezas instead of failing when !POWER_GOOD

If we get this error, we can just try rebooting again and see if it comes
up then.  The POWER_GOOD failures are clustered in time, but it's better
to retry a few times in a row in one job (which has its own 60min timeout)
than to spuriously fail someone's pipeline.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6398>
1 file changed