* Fix socket failed bug in rtmp in connection short case

- Not close the socket when receiving GOAWAY frame to implement gracefully stop

- Set stream creator in serialize_request

TODO: 1. socket management 2. window mechanism

Fix bug: Unit test for circuit_breaker occasionally fails

add circuit_breaker_unittest

Circuit breaker

Fix the bug that in the pooled mode, after the isolation occurs, the health check will not be started.