I noticed that after all the recent change shook out, we're
passing an OpenQA_Client instance all over the place which is
actually *used* exactly twice, once in run_openqa_jobs() and
once in get_passed_testcases(). Instantiating an OpenQA_Client
is pretty much free anyway, so instead of all this pass-the-
parcel crap, let's just have those two places instantiate it
when they need it.
I guess in theory we might want to allow for passing in a
differently-configured OpenQA_Client, but eh, it doesn't seem
really compelling, and you can always just change the client
config file. If we really want to allow for it we can just
have those two function accept an optional 'client' argument
and instantiate if it's not provided.