recycle a bad connect to http1 connPool

[alpha-baby]

Describe the bug

Expected behavior

Actual behavior

Steps to reproduce

first：

start sample http server

package main

import (
	"fmt"
	"math/rand"
	"net/http"
	"time"
)

// 根据长度生成一个随机字符串
func RandString(length int) string {
	str := "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	bytes := []byte(str)
	result := []byte{}
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for i := 0; i < length; i++ {
		result = append(result, bytes[r.Intn(len(bytes))])
	}
	return string(result)
}

func ServeHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Printf("[UPSTREAM]receive request %s", r.URL)
	fmt.Println()

	w.Header().Set("Content-Type", "text/plain")
	w.Header().Set("MaxLengthHeaderKey", RandString(100))

	fmt.Fprintf(w, "Method: %s\n", r.Method)
	fmt.Fprintf(w, "Protocol: %s\n", r.Proto)
	fmt.Fprintf(w, "Host: %s\n", r.Host)
	fmt.Fprintf(w, "RemoteAddr: %s\n", r.RemoteAddr)
	fmt.Fprintf(w, "RequestURI: %q\n", r.RequestURI)
	fmt.Fprintf(w, "URL: %#v\n", r.URL)
	fmt.Fprintf(w, "Body.ContentLength: %d (-1 means unknown)\n", r.ContentLength)
	fmt.Fprintf(w, "Close: %v (relevant for HTTP/1 only)\n", r.Close)
	fmt.Fprintf(w, "TLS: %#v\n", r.TLS)
	fmt.Fprintf(w, "\nHeaders:\n")

	r.Header.Write(w)
}

func main() {
	http.HandleFunc("/", ServeHTTP)
	http.ListenAndServe("127.0.0.1:8080", nil)
}

second：

start mosn with json config as follows

{
	"disable_upgrade" : true,
	"servers":[
		{
			"default_log_path":"stdout",
			"default_log_level":"DEBUG",
			"routers":[
				{
					"router_config_name":"server_router",
					"virtual_hosts":[{
						"name":"serverHost",
						"domains": ["*"],
						"routers": [
							{
								"match":{"prefix":"/"},
								"route":{"cluster_name":"serverCluster"}
							}
						]
					}]
				}
			],
			"listeners":[
				{
					"name":"serverListener",
					"address": "127.0.0.1:2046",
					"bind_port": true,
					"filter_chains": [{
						"filters": [
							{
								"type": "proxy",
								"config": {
									"downstream_protocol": "Http1",
									"upstream_protocol": "Http1",
									"router_config_name":"server_router",
                                  "extend_config": {
                                    "max_header_size": 100
                                  }
								}
							}
						]
					}]
				}
			]
		}
	],
	"cluster_manager":{
		"clusters":[
			{
				"name":"serverCluster",
				"type": "SIMPLE",
				"lb_type": "LB_RANDOM",
				"max_request_per_conn": 1024,
				"conn_buffer_limit_bytes":32768,
				"hosts":[
					{"address":"127.0.0.1:8080"}
				]
			}
		]
	},
	"admin": {
		"address": {
			"socket_address": {
				"address": "0.0.0.0",
				"port_value": 34902
			}
		}
	}
}

Minimal yet complete reproducer code (or GitHub URL to code)

Environment

• MOSN Version