OF-3306: Reduce memory footprint of Pubsub subscription
The issue in OF-3306 relates to a large amount of `NodeSubscription` instances being loaded in memory. This commit does not address that, but does significantly reduce the memory footprint of each instance. This helps reduce the impact of the issue.
The memory footprint is reduced by switching from a Logger-instance per instance, to a static one that's shared with all instances.
In one heap dump that was analyzed, these Logger instances accounted for (very roughly) 15% of the heap size.
Dave Cridland <dave@cridland.net>
1629843d732af3e6fe6f161a8e1acaeee0815ed9
Remove unused BlockingReadingMode and SocketReader classes
