bug: admin API response with Transfer-Encoding but no length in body

[qizhendong1]

Current Behavior

I found admin api response using chunked header and response all data once but no length is body.

ref https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Transfer-Encoding

Expected Behavior

No response

Error Logs

No response

Steps to Reproduce

1. put a route

curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -i -d '
{
    "uri": "/*",
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:8899": 10
        }
    }
}

2. get the route

curl http://127.0.0.1:9180/apisix/admin/routes/ -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -i

Environment

• APISIX version (run apisix version): 3.2.2
• Operating system (run uname -a): centos 7.9
• OpenResty / Nginx version (run openresty -V or nginx -V): openresty/1.21.4.2
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):