Stop sending connection_stats from protocol readers to rabbit_event.
Stop sending queue_stats from queues to rabbit_event.
Sending these stats every 5 seconds to the event manager process is
superfluous because noone handles these events.
They seem to be a relict from before rabbit_core_metrics ETS tables got
introduced in 2016.
Delete test head_message_timestamp_statistics because it tests that
head_message_timestamp is set correctly in queue_stats events
although queue_stats events are used nowhere.
The functionality of head_message_timestamp itself is still tested in
deps/rabbit/test/priority_queue_SUITE.erl and
deps/rabbit/test/temp/head_message_timestamp_tests.py
Michael Klishin
Michal Kuratczyk
Michael Klishin
Michael Klishin
David Ansari
Philip Kuryloski