Improve deadlock detection by using a global notion of progress

Instead of tracking each response indepently, use a global notion of progress by counting all tracking responses. This will still warn about the deadlock in the Wasserportal RLP harvester, but do not emit spurious warnings in the GDK Bayern harvesters.

It also reduces the amount of log message spam by having only of the current set of waiters emit the warning messages instead of all of them which should essentially yield a rate of logging this warning once per minute if the deadlock persists.