When using JIT runners, we register the runner on GitHub before we get
a chance to spin up the instance in the provider. In such cases, we end
up with a runner in "offline" state while we're creating the actual resource
that will embody the runner. This change will give runners a chance to come
online before garm tries to clean them up.
Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>