Replace specialized `firehose_triggers_in_block` by direct usage of `…

…TriggerAdapter::triggers_in_blocks` (graphprotocol#3082)

With the revamped `FirehoseBlockStream`, it's now possible to directly re-use the `TriggerAdapter::triggers_in_blocks` code instead of relying on our specialized `firehose_triggers_in_block`. This make the code more re-usable.

Eliminated at the same time a useless close in `NearChair::TriggersAdapter`. Also make some `NearChain` now panics instead of silently returning something that is not good.

Linked to graphprotocol#3080

Co-authored-by: Matthieu Vachon <[email protected]>

chain head listener: could log be reordered?

chain head listener: add blocking thread pool contention check

chain head listener: more logs

chain head listener: change watcher deadlock detection to avoid spuri…

…ous deadlock detection

chain head listener: change watcher deadlock detection to avoid spuri…

…ous deadlock detection

chain head listener: add number to logging contexts

chain head listener: switch atomic for mutex

chain head listener: moar moar logs

chain head listener: moar logs