openqa: use get_jobs, handle connection errors, fix a bug
get_jobs is a simpler job getting thing I just added to the
client; we don't need the elaboration of iterate_jobs any more.
Handle connection errors (we didn't before). Handle 'no jobs'
and 'still running jobs' cases differently now.
There was a bug in the 'update the 'last built' data if we
don't find the image' loop: it would update the data alright,
but it wouldn't re-do the match, because that's inside the
'while' loop and once the data was added we broke out of the
loop. So rejig the loop logic a bit so the match is re-done
after the data is updated.