Remove hack in chain_head_listener

[leoyvens]

This was added in a time when we were having problems with receiving chain head updates and were trying workarounds. This one had a hypothesis of a deadlock in tokio Watch::send. I was never able to corroborate this, no other tokio user ever reported something like this and improvements have since been made to the internals of Watch. So there isn't much justification for keeping this hack.

[leoyvens]

I tried this on a canary build in studio and it resolved some of the no chain head update for 30 seconds, polling for update logs, which is a great result.