fix conn pool grid test (#19202)
fix conn pool grid test (#19202)

Signed-off-by: Dan Zhang <36efad70d3f1f474276ceb30cb7b5f71fd2c3a8c@google.com>

envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy