Remove it from request handler since there's already the context of the
request path, added through TraceLayer.

They are no longer needed in the 2021 edition.

Upgrades Ruma again to make this work.

Should make the code a little bit easier to read.

Co-authored-by: Timo Kösters <timo@koesters.xyz>

We now ask the trusted server for all keys in 1 request, instead of
asking each server individual for it's own keys.

Conduit did not send the event in /sync because of a race condition.
There is a brief moment in time where Conduit accepted the event, but
did not store it yet. So when the client /syncs it updates the since
token without sending the event. I hope I fixed it by significantly
shortening the race-condition period.