deproxy_client.py - we must not use STATE_STARTED as abort_cond for wait_for_connection_close because handle_close, etc. can change the state (for example handle_close method change status: STATE_STARTED -> STATE_STOPPED). Then wait_for_connection_close will return None, but it is unexpected. So the STATE_ERROR state can be used as abort_cond;
lxc_server.py sometimes needs more time to close on CI;
rework test_wait_for_headers_frame test using a new option in DeproxyClientH2 - auto_flow_control.
STATE_STARTEDasabort_condforwait_for_connection_closebecausehandle_close, etc. can change the state (for examplehandle_closemethod change status:STATE_STARTED->STATE_STOPPED). Thenwait_for_connection_closewill return None, but it is unexpected. So theSTATE_ERRORstate can be used asabort_cond;test_wait_for_headers_frametest using a new option in DeproxyClientH2 -auto_flow_control.