fix: emit false on active$ after replication is done

[maxnowack]

It seems that the fix for #4117 in #4124 was not complete. However, the provided test case wasn't complete either.
I've extend the test case to also test if false is emitted after replication has completed.

[pubkey]

Test looks good.
I do not have time to fix this, please investigate.

[maxnowack]

I've already tried to. It seems that these lines will never be executed.
I've tried to investigate further, but I'm to unfamiliar with the replication internals right now.
Do you have any idea which part I should look at more closely?

[pubkey]

I think that is the correct part to look at but I have no idea why these lines do not get executed.

[maxnowack]

Okay, I'll try to dig into it.

[maxnowack]

Maybe I have some potential fix.
I've changed the addNewTask method, so that state.events.active.down.next(false) gets called always after the task processing inside of the state.streamQueue.down promise.
I also had to move state.firstSyncDone.down.next(true) in front of it. Otherwise awaitInitialReplication would finish before active$ emits false after the first replication.
This has the implication that firstSyncDone.down now also emits true after downstreamProcessChanges is finished first.
Please look over it carefully, as I'm not really sure if that is fine or maybe has some other impact I'm now yet aware of.

[pubkey]

I merged this. I am not sure if it is 100% correct but I think it is an improvement compared to the current behavior and as long as the tests are green I am confident that nothing major could be broken.

[pubkey]

Added this to the changelog here: f96d264