* chore: harmonize OSS and Enterprise subscriber initialization
* refactor: chanwriter close blocks until chanwriter is flushed
* refactor: remove redundant state
* test: add test for blocked subscriber during subscription update
* fix: blocked subscriber does not fail subscription update
* fix: only iterate matching subscriptions
* fix: use serialized points in subscriber queues
* feat: add total-buffer-bytes config parameter to subscriptions
* fix: put subscription serialization on the write path
* fix: subscription service only needs regular mutex, not RWMutex
* fix: review comments
* chore: update changelog