test: clientv3 integration tests with proxy

test

@@ -134,6 +134,7 @@ function integration_e2e_pass {
 
 function grpcproxy_pass {
 	go test -timeout 15m -v ${RACE} -tags cluster_proxy -cpu 1,2,4 $@ ${REPO_PATH}/integration
+	go test -timeout 15m -v ${RACE} -tags cluster_proxy -cpu 1,2,4 $@ ${REPO_PATH}/clientv3/integration
 }
 
 function release_pass {