Address JMS Hybrid Threading Approach

[volosied]

When we switched to epoll, we noticed JMS failures with packet ordering / heartbeat. Differences with epoll and nio, caused these failures. The fix was to ensure writes occurred within the event loop from the Liberty threads. See #34036

Bob's assessment (general guideline)

1. Have Netty handlers immediately dispatch to Liberty thread pools after reads

2. Have Liberty threads own the entire request/response lifecycle

3. Have Liberty threads submit writes back through a proper queue/channel

4. Remove the mixed threading model