add more diagnostic logs (#8153)
add more diagnostic logs (#8153)

Istio sets listener filter timeout to 10ms by default but requests fail from time to tome. It's very difficult to debug. Even though downstream_pre_cx_timeout_ is exposed to track the number of timeouts, it would be better to have some debug logs.

Description: add more diagnostic logs
Risk Level: low

Signed-off-by: crazyxy <2cfb40f243ed141a27fe798237c69a61c7aa885f@google.com>
lizan/envoy,lyft/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy,eklitzke/envoy,envoyproxy/envoy,lyft/envoy,eklitzke/envoy,eklitzke/envoy,lizan/envoy,envoyproxy/envoy-wasm,jrajahalme/envoy,jrajahalme/envoy,lizan/envoy,istio/envoy,istio/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,jrajahalme/envoy,envoyproxy/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy,lizan/envoy,istio/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy,lyft/envoy,jrajahalme/envoy,jrajahalme/envoy,lyft/envoy,envoyproxy/envoy,lyft/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,jrajahalme/envoy,eklitzke/envoy,envoyproxy/envoy-wasm,istio/envoy,lizan/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,eklitzke/envoy,istio/envoy,eklitzke/envoy,lyft/envoy,envoyproxy/envoy