[Triage] gthread evolution: lifecycle of an accepted connection

[aszubarev]

Instead of waiting for client data in a pool thread, we can wait for it in the main thread — an approach similar to what was used in versions v21.0.0 to v23.0.0. But this time, set a timeout for the connection. When the connection expires, it will be closed in the murder_pending method.

Advantages:

• Also works with fast connection
• Also works during a graceful shutdown (thx v24+)
• Avoids creating temporary poller for prevent thread pool exhaustion
• No blocking of the thread even for 5 seconds!

Closes #3634