Why are these values hardcoded Send_timeout, client_body_timeout in a template configmap?

Hello,

I’m trying to understand the configuration in `apisix/helm-charts/templates/configmap.yaml`.

I noticed this section:

```yaml
keepalive_timeout: {{ .Values.apisix.nginx.keepaliveTimeout | quote }}
client_header_timeout: 60s # timeout for reading client request header, then 408 (Request Time-out) error is returned to the client
client_body_timeout: 60s # timeout for reading client request body, then 408 (Request Time-out) error is returned to the client
send_timeout: 10s # timeout for transmitting a response to the client, then the connection is closed
```

Instead of using a more dynamic configuration like:

```yaml
client_header_timeout: {{ default "60s" .Values.apisix.nginx.clientHeaderTimeout }}
client_body_timeout: {{ default "60s" .Values.apisix.nginx.clientBodyTimeout }}
send_timeout: {{ default "10s" .Values.apisix.nginx.sendTimeout }}
```

Why are these values hardcoded instead of being configurable through `values.yaml`?

Start with apisix/helm-charts/templates/configmap.yaml and compare the existing keepaliveTimeout handling with values.yaml. Check how the proposed clientHeaderTimeout, clientBodyTimeout, and sendTimeout values would be represented and confirm that defaults preserve the current behavior while allowing overrides.

Written by the indexing model from the issue text.