Support Prometheus output

update avalanche.md

string_splitter supports embedded '\0' characters and separator can be '\0'

bug fix: consul ns thread can not quit

wrr lb algo enhancement

Update server.md

删除错别字。

fix a typo in docs

circuit_breaker optimization 

Update combo_channel.md

Exposing the status of CircuitBreaker to the builtIn page

add server processed time in controller

modify the diff value in grpc timeout test