Adds a proactive handler that rejects new requests with HTTP 429's when the
queue has been blocking for more than 10 consecutive seconds, allowing back-
pressure to propagate in advance of filling up the connection backlog queue.

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Co-authored-by: Mashhur <[email protected]>

Upgrade netty to 4.1.118

Bump netty and prepare for release

…bserverTest.java

Co-authored-by: Rye Biesemeyer <[email protected]>

Local compaction depends on completion order and timing. Under certain cases
node count can reach or exceed `sqrt(concurrency)` before the final compaction
is triggered. The test for intermediate state was failing fairly often in CI.
This commit updates the test for intermediate state to simply be less than
`concurrency`. This should satisfy the intent of the test, with the added
security of the rest of the test asserting the finalized state is less than 2
nodes.

Backport test fix