faa9a74c9e99eb43ba0d27fa906767ee88011aeb test: Fail wait_until early if connection is lost (MarcoFalke)
Pull request description:
Calling `minonode.wait_until` needs a connection to make progress (e.g. waiting for an inv), unless the mininode waits for the initial connection or for a disconnection. So for test development and failure debugging, fail early in all `wait_until`, unless opted out.
Depends on D9514
Backport of core#19489